Step 1

Preheat oven to 325°F. Grease a 9x13-inch baking pan with butter or cooking spray, set aside.

Step 2

Blend cake mix, flour, sugar, and salt together in a bowl. Set aside.

Step 3

In a separate bowl, mix together sour cream, egg whites, water, oil, and vanilla. Fold dry ingredients into wet. Beat on medium speed for 3 minutes, scraping sides of bowl after 2 minutes.

Step 4

Pour batter into greased baking dish. Spoon cherry pie filling over top of batter, and gently spread to edges.

Step 5

Bake for 45-50 minutes. Cool completely before serving.