CAKE: Preheat oven to 350 degrees. Line two jelly roll pans with parchment paper and spray with non-stick cooking spray.
Prepare cakes separately according to package instruction. Pour batters into prepared pans and bake for 10-12 minutes or until a toothpick inserted comes out clean. Cool completely.
CREAM CHEESE FROSTING: With an electric mixer, beat together cream cheese and butter until smooth. Turn mixer to low speed, and add confectioners' sugar, salt and vanilla extract. Turn mixer on high and beat until light and fluffy. Fill a piping bag, fitted with a star tip, with cream cheese frosting.
ASSEMBLE PUSH POPS: Using a Push Pop container as a cake cutter, cut the cakes to size, trim with a knife if necessary.
Push a blue cake cut-out (using a trimmed base & stick) into the push pop container, pipe in frosting, and add a sprinkles if desired, repeat with red cake cut-out. Top with frosting and sprinkles.