Black forest trifle

1 (8 ounce) package chocolate sugar-free, low-fat cake mix (such as Sweet `N Low)
3/4 cup water
1 (1 ounce) box chocolate sugar-free, fat-free instant pudding mix
2 cups fat-free milk
1 (16 ounce) package frozen no-sugar-added pitted cherries
2 drops red food coloring
2 cups fat-free frozen whipped topping, thawed
Sugar-free chocolate curls (optional)

1. Prepare cake mix according to package directions, using 3/4 cup water. Let cake cool in pan; remove from pan, cut into cubes.
2. Prepare pudding mix according to package directions, using 2 cups fat-free milk; chill at least 30 minutes.
3. Thaw cherries, reserving 1/4 cup juice. Combine cherries, juice, and food coloring.
4. Place half of cake cubes in a 3-quart trifle bowl. Spoon half of cherries over cake; spread 1 cup pudding over cherries, and top with half of whipped topping. Repeat layers. Top with chocolate curls. Cover and chill at least 8 hours.