Stir together 1 1/4 cups water and 2 tablespoons instant coffee granules until completely dissolved.
Prepare cake mix according to package directions, substituting coffee mixture for water.
Pour batter into 3 greased and floured 8-inch cakepans.
Bake at 350° for 18 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 to 15 minutes; remove from pans, and cool completely on wire racks.
Beat butter at medium speed with an electric mixer until creamy; gradually add powdered sugar, beating at low speed until blended.
Add remaining 2 tablespoons coffee granules, cocoa, and cream, beating until blended.
Brush cake layers evenly with coffee liqueur, if desired.
Spread cocoa mixture between cake layers. Spread Mocha Frosting on top and sides of cake. Garnish, if desired.
Note: For testing purposes only, we used Pillsbury Moist Supreme Devil's Food Cake Mix and Kahlúa for coffee liqueur.
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