Preheat oven to 350F. Spray 2 8-inch round cake pans with cooking spray.
In a large bowl, beat 1 box cake mix and ingredients called for on box with electric mixer on low speed 30 seconds, then on high speed about 2 minutes or until smooth. Spread in pans.
Bake for 30-35 minutes. Loosen cakes with a knife and remove from pans.
Repeat process with the second cake mix, to make 2 more layers.
Transfer cake to a cooling rack and let it cool completely.
Flatten each cake layer, if tops are domed. Using a serrated knife, carefully cut each layer into 2 layers with the same thickness.
In 4 of the layers, cut 4-inch circles out of the center, using a round 4-inch cutter.
To assemble the cake:
Place 1 uncut layer on the bottom of a cake platter. Spread frosting on top.
Add one of the cut layers and spread frosting on top. Repeat with the remaining cut layers, spreading frosting on top of each one. Fill cake with candy.
Top with the second uncut layer. Spread frosting on top and the sides of the cake.
Using your hands, press sprinkles to the sides of the cake. Add sprinkles on top if the cake, too.
Add boy/girl labels on top. .