Preheat oven to 325°F (165°C). Line an 8x8 inch baking pan with parchment paper, leaving an overhang on two sides.

In a medium saucepan over medium-low heat, melt 1 cup of butter. Whisk in granulated sugar, cocoa powder, and ½ tsp salt. Whisk constantly for 2-3 minutes until hot, glossy, and slightly pulling from pan sides. Remove from heat and let cool for 5 minutes.

Whisk vanilla extract into the warm chocolate mixture. Add eggs one at a time, whisking vigorously after each until batter is smooth and shiny.

Switch to a spatula and gently fold in the flour until just combined and no dry streaks remain.

Spread the thick batter evenly into the prepared pan. Bake for 25-30 minutes, until a toothpick inserted into the center comes out with a few moist crumbs attached.

Let the brownies cool completely in the pan on a wire rack.

Once cool, use a pastry brush or spoon to evenly drizzle ¼ cup of Baileys over the entire surface of the brownies. Let it soak in.

For the frosting: In a medium bowl, beat the softened ½ cup of butter on medium speed until smooth and creamy, about 2 minutes.

With mixer on low, gradually add the sifted powdered sugar until fully incorporated.

Increase speed to medium and add ⅓ cup of Baileys and a pinch of salt. Beat for 2-3 minutes until light, fluffy, and spreadable. Adjust consistency with more powdered sugar or Baileys if needed.

Spread the frosting evenly over the soaked brownies. Garnish with chocolate shavings or a dusting of cocoa powder if desired.

Cover the pan and refrigerate for at least 2-3 hours, or ideally overnight, to set before cutting into squares.