Preheat oven to 400°F (200°C). Bake the potatoes directly on the oven rack for 45-60 minutes, or until easily pierced with a fork. Let cool slightly.

While potatoes are baking, cook bacon until crisp. Remove bacon and set aside, reserving 2 tablespoons of bacon fat. In a large pot or Dutch oven, melt butter and reserved bacon fat over medium heat. Add onion and cook until softened, about 5-7 minutes. Add garlic and cook for 1 minute more, until fragrant.

Once the potatoes are cool enough to handle, cut them in half and scoop out the flesh, leaving the skins behind. Add the potato flesh to the pot with the onion and garlic.

Pour in the chicken broth. Bring to a simmer, then reduce heat and cook for 15 minutes, allowing the potatoes to break down slightly.

For a smoother soup, use an immersion blender to partially blend the soup. Be careful not to over-blend, as this can make the soup gluey. Alternatively, transfer about 2 cups of the soup to a regular blender, blend until smooth, and return it to the pot.

Stir in the heavy cream, cream cheese, and cheddar cheese. Cook over low heat until the cheeses are melted and the soup is smooth, about 5-7 minutes.

Season with salt, pepper, garlic powder, and smoked paprika. Stir in the chopped chives and crumbled bacon (reserve some for topping).

Ladle the soup into bowls and garnish with additional shredded cheese, bacon crumbles, chives, and a dollop of sour cream or Greek yogurt, if desired.