Pre-heat oven to 350°F. Lightly grease and flour two 9 inch round baking pans.
In the bowl of a stand mixer, stir together the flour, sugar, cocoa powder, baking powder, baking soda, salt and espresso powder.
Add the milk, baileys, vegetable oil, eggs and vanilla extract to the dry ingredients. Beat on medium speed until well combined.
With the mixer set to low speed, slowly add the boiling water, stirring until combined.
Divide the cake batter between the two baking pans. Bake for 30-35 minutes, or until a tester comes out clean.
Let the cakes cool for about 10 minutes before removing from pans. Ensure the cakes are completely cooled before frosting.