In the mixing bowl of a stand mixer, blend the butter until creamy and smooth.
Add the vanilla, and blend well.
Add the powdered sugar and continue to blend until smooth.
Place about 1/3 of the frosting in a separate bowl to save.
Place another 1/3 of the frosting in a pastry bag, with a large star tip and place in the refrigerator.
In the mixing bowl, add the food coloring gel and mix until well blended, scraping down the sides of the bowl to mix all frosting. If the frosting is not as bright a pink color as you'd like, add a little more red or pink food coloring gel, until desired shade of pink is achieved.
Frost the cooled cake with the white frosting you held back, and let it sit in the refrigerator for 30 minutes.
Frost the cake with the pink layer of frosting and make swirls on the pink layer.
Pipe small dollops of white frosting from the pastry bag all over the top of the cake.
Sprinkle with colored sprinkles. Add other decorations on top of the cake if desired.
Cut the cake in 3 inch square pieces and Enjoy!