Preheat oven to 350 degrees. Coat two 8 inch round pans with nonstick cooking spray, set aside. With a mixer at low speed, mix together the eggs, butter, yogurt and milk. Add dry cake mix and blend until well incorporated, about one minute.
Divide batter evenly into prepared pans and bake 20-25 minutes or until a toothpick inserted in the center comes out clean. Cool cakes 5 minutes, then carefully remove from pans and cool completely on a wire rack.
Using your hands, crumble cake into small pieces and place in a large bowl, set aside. Place ice cream and milk into a blender and mix until smooth. Add 4 cups of cake crumbs and blend on high to combine. Add rainbow sprinkles and pulse once or twice to incorporate.
Divide between four glasses, top with whipped cream and garnish with remaining cake pieces.