Preheat oven to 325°F and grease a 9x13-inch cake pan with butter and set aside.
In a large bowl or stand mixer, whisk together the cake mix, dry pudding mix, flour, and sugar.
Beat in the flavor emulsion, milk, sour cream, and egg whites just until combined.
Pour the batter into the prepared baking pan and bake for 28 to 30 minutes or until a toothpick comes clean from the center.
Allow the cake to cool completely in the pan before frosting.
Prepare the cream cheese frosting by creaming together the butter and cream cheese in a large bowl or stand mixer fitted with a paddle attachment at medium speed for 2 to 3 minutes.
Add in vanilla extract and powdered sugar 1 cup at a time, beating at low speed after each addition just until incorporated. Then increase the speed to high and beat for an additional 2 minutes until silky smooth.
Spread the frosting over the top of the cooled cake and top with sprinkles!