Preheat oven to 350 degrees. Spray a 9x13 cake pan with nonstick cooking spray.
Combine the water and espresso powder. Heat for 1 minute in the microwave. Stir well.
3/4 cup Water, 2 Tablespoons Espresso Powder
In a large bowl, combine the cake mix, espresso, oil, and eggs. Mix well. Pour into prepared cake pan and bake according to package directions.
1 box Cake Mix, 1/2 cup Vegetable Oil, 3 Eggs
In a small bowl, combine Kahlua and sweetened condensed milk.
1/2 cup Kahlua, 1 cup Sweetened Condensed Milk
Once done, remove from the own and poke holes in the top of the cake {I used lollipop sticks}. Pour Kahlua mixture on the top of the cake and refrigerate until cooled.
Frosting
Melt the butter in a saucepan over medium heat. Whisk in the cocoa and bring the mixture to a boil. Remove from heat and whisk in the Kahlua, vanilla, and milk.
1/2 cup Butter, 1/4 cup Unsweetened Cocoa, 3 Tablespoons Kahlua, 2.5 Tablespoons Milk, 1 teaspoon Vanilla Extract
While whisking continuously, add powdered sugar in 1 cup increments. Spread over cooled cake. Let sit for 10 minutes before serving.
3 cups Powdered Sugar
Notes
You can use yellow or chocolate cake mix for this recipe.