Preheat oven to 350F
Boil 280g Guinness for 5-6 minutes until it reduces
Pour 240g (1 cup) reduced Guinness into a bowl and add cocoa powder, whisking till dissolved
Stream in neutral oil while whisking
Add granulated sugar and brown sugar
Mix in vanilla extract and eggs
Combine milk and sour cream then add to wet ingredients
Mix all dry ingredients (flour, baking soda, baking powder, salt) in a separate bowl
Add dry ingredients to wet ingredients, whisking until no lumps remain
Pour evenly into 2 greased and lined 8-inch cake pans
Bake at 350F for 40-50 minutes until a toothpick comes out clean
Let cool in pan for 5 minutes then turn onto a wire rack and cool completely
Beat together browned butter and cream cheese until smooth
Add powdered sugar and combine
Add Baileys Irish Cream, vanilla extract, and salt
Trim the tops of each cake layer
Frost the cake, leaving the sides bare to mimic a pint of Guinness
