Brown the Butter: In a saucepan over medium heat, melt the unsalted butter. Continue cooking, stirring occasionally, until the butter turns a golden brown color and emits a nutty aroma. This should take about 5-7 minutes. Once browned, remove the butter from heat and allow it to cool to room temperature.
Preheat Oven: Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Cream Butter and Sugars: In the bowl of a stand mixer fitted with the paddle attachment, cream together the cooled brown butter, granulated sugar, and dark brown sugar until light and fluffy, about 2-3 minutes.
Incorporate Dry Ingredients: Gradually add the dry ingredients to the wet ingredients in the mixer bowl. Mix on low speed until just combined.
Fold in Chocolate Chips: Gently fold in the semi-sweet chocolate chips and Baileys chocolate chips until evenly distributed throughout the dough.
Scoop and Chill Dough: For convenient chilling, scoop your Bailey's Chocolate Chip Cookie dough into a 9 by 13-inch pan—it fits perfectly on a shelf in the refrigerator! Remember, this step is just to cool the dough; we won't be baking on this pan. When it's time to bake, simply transfer the chilled cookie dough scoops onto a parchment-lined baking sheet, ensuring they're evenly spaced.
Bake: Bake in the preheated oven for approximately 12 minutes or until the edges are golden brown and the centers are set. Allow the cookies to cool slightly on the baking sheet before transferring them to a wire rack to cool completely.