Prepare cake mix according to package directions in a 13x9 inch cake pan. Let cake cool in pan; remove from pan, cut into cubes.
Prepare pudding mix according to package directions, using 2 cups milk; chill at least 30 minutes.
Place half of cake cubes in a 3 qt. trifle bowl. Spoon half of cherries over cake; spread 1 cup of pudding over cherries, and top with half of the whipped topping. Repeat layers. Top with chocolate curls, if desired.