ULTIMATE FRENCH ONION POTATOES AU GRATIN

I’ll never forget the Thanksgiving where my Aunt Carol, notorious for her experimental (and sometimes disastrous) dishes, unveiled a bubbling casserole dish that had everyone whispering; thankfully, this time it was out of pure amazement! That glorious creation turned out to be her take on French Onion Potatoes Au Gratin, and it was the sleeper hit of the entire meal. Today, I’m sharing my perfected version of this comforting classic, promising you a dish so decadent and flavorful, it’ll become a staple in your own family gatherings. 

Let’s Talk French Onion Potatoes Au Gratin: The Ultimate Comfort Food

Okay, friend, let’s be honest: potatoes au gratin is already pretty close to perfect, right? Creamy, cheesy, comforting… it’s got it all. But what happens when you take that perfection and infuse it with the deep, savory, caramelized goodness of French onion soup? Magic, that’s what! This French Onion Potatoes Au Gratin recipe is a game-changer, taking a beloved side dish to a whole new level of flavor complexity. We’re talking layers of thinly sliced potatoes, sweet caramelized onions, Gruyère cheese (oh yes!), and a creamy, dreamy sauce that will have everyone begging for seconds (and thirds!).

Don’t let the “French Onion” part intimidate you. While it might sound fancy, it’s surprisingly easy to make. We’re just taking the classic flavors of French onion soup – caramelized onions, beef broth, and that amazing Gruyère – and incorporating them into the already fantastic world of potatoes au gratin. Think of it as a delicious fusion of comfort food royalty!

Why You’ll Absolutely Love This Recipe

• Unbelievable Flavor: The combination of sweet caramelized onions, nutty Gruyère, and creamy potatoes is simply irresistible. It’s a flavor explosion in every bite!
• Impressive Yet Easy: This dish looks and tastes incredibly sophisticated, but it’s surprisingly straightforward to make. You’ll impress your guests without spending hours in the kitchen.
• Perfect for Any Occasion: Whether you’re hosting a holiday dinner, a cozy weeknight meal, or a potluck with friends, this French Onion Potatoes Au Gratin is guaranteed to be a crowd-pleaser.
• Make-Ahead Friendly: You can assemble this dish ahead of time and bake it just before serving, making it perfect for busy days.
• Customizable: Feel free to adjust the cheese, herbs, or even add a touch of garlic for your own unique twist.

Ingredients You’ll Need

Here’s what you’ll need to create this masterpiece. Don’t worry, most of these are pantry staples!

• Potatoes: I recommend using Yukon Gold potatoes. They have a creamy texture and hold their shape well during baking. Russet potatoes will also work, but they might be a bit drier. About 2-3 pounds.
• Onions: Yellow onions are the classic choice for French onion soup, and they work perfectly here. You’ll need about 3-4 large onions.
• Butter: For caramelizing the onions and adding richness to the sauce.
• Beef Broth: Adds that signature French onion flavor. I like to use low-sodium broth so I can control the saltiness.
• Heavy Cream: This is what makes the sauce incredibly creamy and decadent. Don’t skimp on it!
• Gruyère Cheese: The quintessential cheese for French onion soup. Its nutty, slightly sweet flavor pairs perfectly with the caramelized onions and potatoes. You can also use a combination of Gruyère and Swiss cheese if you prefer.
• Garlic: Just a clove or two, minced, to add a subtle savory note.
• Fresh Thyme: Adds a lovely herbaceous aroma and flavor. Fresh is best, but dried thyme will also work in a pinch.
• Salt and Pepper: To season everything to perfection.
• Nutmeg: A pinch of freshly grated nutmeg adds a warm, subtle spice that complements the other flavors beautifully.

Step-by-Step Instructions: Let’s Get Cooking!

Alright, let’s get down to business. I’ve broken down the steps to make this French Onion Potatoes Au Gratin as easy as possible.

Step 1: Caramelize the Onions (The Key to Flavor!)

This is arguably the most important step, so don’t rush it! Caramelizing the onions properly is what gives this dish its signature French onion flavor.

1. Slice the onions thinly. I like to use a mandoline for even slices, but a sharp knife works just fine.
2. Melt the butter in a large skillet over medium heat. Add the onions and a pinch of salt.
3. Cook the onions slowly, stirring occasionally, for about 30-45 minutes, or until they are deeply golden brown and caramelized. The key is low and slow! Don’t crank up the heat, or the onions will burn instead of caramelizing.
4. About halfway through, you can add a teaspoon of sugar to help the caramelization process along.
5. Once the onions are caramelized, stir in the minced garlic and fresh thyme. Cook for another minute until fragrant.
6. Pour in the beef broth and scrape up any browned bits from the bottom of the skillet. This adds even more flavor! Simmer for a few minutes until the broth has reduced slightly.
7. Remove from heat and set aside.

Step 2: Prepare the Potatoes

1. While the onions are caramelizing, peel and thinly slice the potatoes. Again, a mandoline is your friend here, but a sharp knife will do the trick. Aim for slices about 1/8 inch thick.
2. Place the potato slices in a bowl of cold water to prevent them from browning.
3. Drain the potatoes and pat them dry with paper towels.

Step 3: Assemble the Au Gratin

Now for the fun part: layering everything together!

1. Preheat your oven to 375°F (190°C).
2. Grease a 9×13 inch baking dish with butter.
3. Arrange a layer of potato slices in the bottom of the dish, slightly overlapping.
4. Spoon about half of the caramelized onions over the potatoes.
5. Sprinkle with about 1/3 of the Gruyère cheese.
6. Repeat the layers: potatoes, onions, cheese.
7. For the final layer, arrange the remaining potato slices on top and sprinkle with the remaining Gruyère cheese.

Step 4: Make the Cream Sauce

This simple sauce is what ties everything together and makes this dish so incredibly creamy.

1. In a saucepan, heat the heavy cream over medium heat.
2. Season with salt, pepper, and a pinch of nutmeg.
3. Bring to a simmer, then remove from heat.
4. Pour the cream sauce evenly over the potatoes in the baking dish. Make sure the sauce gets down into all the layers.

Step 5: Bake!

Time to bake this beauty until it’s golden brown, bubbly, and irresistible.

1. Cover the baking dish with aluminum foil.
2. Bake for 45 minutes.
3. Remove the foil and bake for another 15-20 minutes, or until the potatoes are tender and the cheese is melted and bubbly.
4. Let the au gratin rest for 10-15 minutes before serving. This allows the sauce to thicken slightly and the flavors to meld together.

Tips and Tricks for the Best French Onion Potatoes Au Gratin

Here are a few extra tips to ensure your au gratin is a resounding success!

• Don’t Skip the Caramelization: I can’t stress this enough! The caramelized onions are the heart and soul of this dish. Take your time and let them develop that deep, sweet flavor.
• Use a Mandoline (If You Have One): A mandoline makes quick work of slicing the potatoes and onions evenly. Just be careful and use the hand guard!
• Keep the Potato Slices Thin: Thinly sliced potatoes will cook more evenly and absorb the cream sauce better.
• Don’t Overcrowd the Pan When Caramelizing the Onions: If your skillet is too crowded, the onions will steam instead of caramelizing. Cook them in batches if necessary.
• Season Generously: Don’t be afraid to season the potatoes and onions with salt and pepper. This will bring out their natural flavors.
• Use Freshly Grated Cheese: Pre-shredded cheese often contains cellulose, which can prevent it from melting properly. Freshly grated Gruyère will melt beautifully and have a superior flavor.
• Let it Rest: Allowing the au gratin to rest for 10-15 minutes after baking is crucial. This allows the sauce to thicken and the flavors to meld together, resulting in a more cohesive and flavorful dish.

Variations and Add-Ins

Want to put your own spin on this classic? Here are a few ideas:

• Add Garlic: If you’re a garlic lover, feel free to add a few extra cloves to the onions while they’re caramelizing.
• Spice it Up: A pinch of red pepper flakes will add a subtle kick.
• Different Cheeses: While Gruyère is the classic choice, you can also use a combination of Gruyère, Swiss, and Parmesan cheese.
• Add Bacon: Crispy bacon crumbles would be a delicious addition to this au gratin.
• Vegetarian Version: Use vegetable broth instead of beef broth.
• Herbs: Experiment with different herbs like rosemary, sage, or oregano.

Serving Suggestions

This French Onion Potatoes Au Gratin is incredibly versatile and pairs well with a variety of dishes.

• Main Course: Serve it alongside roasted chicken, steak, or pork. It’s also delicious with a simple green salad.
• Side Dish: It’s a perfect side dish for holiday dinners, potlucks, or any special occasion.
• Breakfast/Brunch: Leftover au gratin makes a surprisingly delicious breakfast or brunch dish. Top it with a fried egg for an extra indulgent treat!

Make-Ahead Instructions

One of the best things about this recipe is that you can make it ahead of time! Assemble the au gratin according to the instructions, but don’t bake it. Cover it tightly with plastic wrap and refrigerate for up to 24 hours. When you’re ready to bake, remove the plastic wrap and bake as directed, adding an extra 10-15 minutes to the baking time if necessary.

Storage and Reheating Instructions

Leftover French Onion Potatoes Au Gratin can be stored in the refrigerator for up to 3 days. To reheat, cover the dish with aluminum foil and bake at 350°F (175°C) until heated through. You can also reheat individual portions in the microwave.

Other Potato Dishes You Might Enjoy

If you’re a potato fanatic like me, here are a few other recipes you might want to try:

Looking for a creamy and comforting soup? Give Crock Pot Crack Potato Soup a try. It’s guaranteed to warm you up on a chilly day. Or, for a cheesy, garlicky delight, check out Cheddar Garlic Herb Potato Soup.

If you’re looking for another creative way to use French onion flavors, I highly recommend French Onion Beef Sloppy Joes. They’re a fun and flavorful twist on a classic comfort food. You could even try French Onion Roast for a hearty and delicious meal.

For a simpler side dish, Garlic Butter Potato Perfection never fails to impress. And of course, who can resist a classic Mac And Cheese? It’s the ultimate comfort food!

French Onion Potatoes Au Gratin Recipe

Ready to make this delicious dish? Here’s the full recipe:

Ingredients:

• 2-3 pounds Yukon Gold potatoes, peeled and thinly sliced
• 3-4 large yellow onions, thinly sliced
• 1/2 cup butter
• 4 cups beef broth
• 2 cups heavy cream
• 2 cloves garlic, minced
• 2 tablespoons fresh thyme leaves
• 8 ounces Gruyère cheese, shredded
• Salt and pepper to taste
• Pinch of nutmeg

Instructions:

1. Preheat oven to 375°F (190°C).
2. Melt butter in a large skillet over medium heat. Add onions and a pinch of salt. Cook, stirring occasionally, for 30-45 minutes, or until deeply golden brown and caramelized.
3. Stir in garlic and thyme. Cook for 1 minute until fragrant.
4. Pour in beef broth and scrape up any browned bits from the bottom of the skillet. Simmer for a few minutes until broth has reduced slightly. Remove from heat.
5. While onions are caramelizing, peel and thinly slice potatoes. Place in a bowl of cold water to prevent browning. Drain and pat dry.
6. Grease a 9×13 inch baking dish with butter.
7. Arrange a layer of potato slices in the bottom of the dish, slightly overlapping.
8. Spoon about half of the caramelized onions over the potatoes.
9. Sprinkle with about 1/3 of the Gruyère cheese.
10. Repeat the layers: potatoes, onions, cheese.
11. For the final layer, arrange the remaining potato slices on top and sprinkle with the remaining Gruyère cheese.
12. In a saucepan, heat heavy cream over medium heat. Season with salt, pepper, and nutmeg. Bring to a simmer, then remove from heat.
13. Pour cream sauce evenly over the potatoes in the baking dish.
14. Cover the baking dish with aluminum foil.
15. Bake for 45 minutes.
16. Remove the foil and bake for another 15-20 minutes, or until the potatoes are tender and the cheese is melted and bubbly.
17. Let the au gratin rest for 10-15 minutes before serving.

Enjoy!

Final Thoughts: Get Ready to Impress!

So there you have it! French Onion Potatoes Au Gratin – a truly spectacular dish that’s surprisingly easy to make. With its layers of creamy potatoes, sweet caramelized onions, and nutty Gruyère cheese, it’s guaranteed to be a hit with everyone who tries it. Don’t be surprised if you find yourself making this recipe again and again. Happy cooking, my friend, and get ready for the compliments to roll in!

ULTIMATE FRENCH ONION POTATOES AU GRATIN

This French Onion Potatoes Au Gratin recipe elevates the classic dish with the rich, savory flavors of French onion soup. Layers of thinly sliced potatoes, sweet caramelized onions, Gruyère cheese, and a creamy sauce create a comforting and impressive side dish perfect for any occasion.

Print Recipe Pin Recipe

Prep Time 30 minutes mins

Cook Time 1 hour hr 5 minutes mins

Total Time 1 hour hr 35 minutes mins

Servings: 6

Course: Side Dish

Cuisine: American, French

Calories: 550

Ingredients Equipment Method Notes

Ingredients

  

• 2-3 pounds Yukon Gold potatoes, peeled and thinly sliced
• 3-4 large yellow onions, thinly sliced
• 1/2 cup butter
• 4 cups beef broth
• 2 cups heavy cream
• 2 cloves garlic, minced
• 2 tablespoons fresh thyme leaves
• 8 ounces Gruyère cheese, shredded
• Salt and pepper to taste
• Pinch of nutmeg
• 1 teaspoon sugar optional

Equipment

• Large Skillet
• Sharp Knife or Mandoline
• Mixing bowl
• Paper towels
• 9×13 inch baking dish
• Saucepan
• Aluminum foil
• Oven

Method

 

1. Preheat oven to 375°F (190°C).
2. Melt butter in a large skillet over medium heat. Add onions and a pinch of salt. Cook, stirring occasionally, for 30-45 minutes, or until deeply golden brown and caramelized.
3. Stir in garlic and thyme. Cook for 1 minute until fragrant.
4. Pour in beef broth and scrape up any browned bits from the bottom of the skillet. Simmer for a few minutes until broth has reduced slightly. Remove from heat.
5. While onions are caramelizing, peel and thinly slice potatoes. Place in a bowl of cold water to prevent browning. Drain and pat dry.
6. Grease a 9×13 inch baking dish with butter.
7. Arrange a layer of potato slices in the bottom of the dish, slightly overlapping.
8. Spoon about half of the caramelized onions over the potatoes.
9. Sprinkle with about 1/3 of the Gruyère cheese.
10. Repeat the layers: potatoes, onions, cheese.
11. For the final layer, arrange the remaining potato slices on top and sprinkle with the remaining Gruyère cheese.
12. In a saucepan, heat heavy cream over medium heat. Season with salt, pepper, and nutmeg. Bring to a simmer, then remove from heat.
13. Pour cream sauce evenly over the potatoes in the baking dish.
14. Cover the baking dish with aluminum foil.
15. Bake for 45 minutes.
16. Remove the foil and bake for another 15-20 minutes, or until the potatoes are tender and the cheese is melted and bubbly.
17. Let the au gratin rest for 10-15 minutes before serving.

Notes

Don’t skip the caramelization step for the onions. Use a mandoline for even slicing. Keep potato slices thin. Season generously. Use freshly grated cheese. Leftovers can be stored in the refrigerator for up to 3 days and reheated in the oven or microwave. Variations include adding extra garlic, red pepper flakes, different cheeses (Swiss, Parmesan), crispy bacon crumbles, or using vegetable broth for a vegetarian version. Experiment with herbs like rosemary, sage, or oregano. Assemble the au gratin ahead of time and refrigerate for up to 24 hours before baking.