For Cake: HEAT oven to 350°F. Coat two 9-inch round cake pans with no-stick cooking spray. Combine cake mix, 1 cup brewed coffee, oil and eggs in large bowl with electric mixer until moistened. Beat 2 minutes on medium speed. Pour into prepared pans.
BAKE 29 to 33 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes. Remove from pans and place on cooling rack to cool completely.
For Butter Mocha Frosting: COMBINE powdered sugar, cocoa and salt in large bowl. Beat in butter with electric mixer on low speed. Gradually add coffee, vanilla and enough milk to make a smooth and spreadable frosting. Spread frosting between layers, on top and sides of cake.
*To make strong brewed coffee: Measure 1/4 cup Millstone® Bed & Breakfast Blend® Coffee for each 1 1/2 cups water. Brew as desired.