Dissolve 2 Tbsp instant coffee in 1 cup boiling water.
Combine 1 pkg (4 serving size) chocolate instant pudding, 1 pkg (2-layer) chocolate cake mix, 4 eggs and 1/4 cup vegetable oil in large bowl; add coffee. Blend well, then beat at medium speed of electric mixer for 2 minutes.
Pour into a greased 13 x 9 baking pan. Bake for 30 - 35 minutes. Cool for 15 minutes. Remove cake from pan and cool on rack.
Spread cake with 1 - 500ml tub of thawed Cool Whip. Sprinkle cake with 1 square grated semi sweet chocolate.