Preheat the oven to 350°F. Grease a 9x13 pan and set aside.
In a large microwave-safe bowl, melt butter. Add in brown sugar and whisk until smooth. Add the eggs, vanilla and Baileys and whisk.
In a medium bowl, whisk together the flour, baking soda, baking powder. Pour flour into wet mixture and mix until combined.
Pour batter into 9 x 13 pan. Even out and smooth top with spatula.
Bake for 30 minutes or until a toothpick comes out clean. Allow to cool completely before cutting and serving.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.