Heat oven to 350°F. Grease two 9 inch cake pans, line with parchment paper, then grease and flour that as well. In a pinch, you can use wax paper.
Stir together sugar, flour, cocoa, baking powder, baking soda and salt in large bowl. Add eggs, milk, oil, and vanilla; beat on medium speed of mixer 2 minutes. Stir in boiling water (batter will be thin). Pour batter into prepared pans.
Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes; remove from pans to wire racks. Cool completely.
To Make the Frosting
Beat the butter until it is soft and fluffy.
Add the vanilla and coffee and continue to beat.
Slowly start adding the powdered sugar a little at a time.
When you notice that the frosting has begun to ball up like a dough, it is time to add the milk. Do not add it all at once, just a little at a time until you have the right consistency.
Add the cocoa and continue to beat until the cocoa is completely incorporated.
Notes
Quick notes for the cake You will not be able to taste the coffee. It just makes the chocolate more chocolate tasting.
Scan for full nutrition info and step-by-step photos.