Lemon Pudding Poke Cake

1 pkg. (2-layer size) white cake mix
2 egg whites
1-1/3 cups water
1 qt. (4 cups) cold milk
2 pkg. (4-serving size each) JELL-O Lemon Flavor Instant Pudding & Pie Filling

Prepare and bake cake mix as directed on package for 13x9-inch baking pan, using 2 egg whites and 1-1/3 cups water. Remove from oven. Immediately poke holes down through cake to pan with round handle of wooden spoon. (Or, poke holes with a plastic drinking straw, using turning motion to make large holes.) Holes should be at 1-inch intervals.

Pour milk into large bowl. Add pudding mixes. Beat with wire whisk 2 minutes. Immediately pour about half of the thin pudding mixture evenly over warm cake and into holes to make stripes. Let remaining pudding mixture stand until slightly thickened. Spoon over top of cake, swirling to "frost" cake.

Refrigerate at least 1 hour or until ready to serve. Cut into 24 squares. Store cake in refrigerator.