In a medium size bowl, mix together the flour, sugar, softened butter and 1/4 cup colored sprinkles. Press this mixture into the bottom of an 8" square baking pan that has been sprayed with cooking spray. Bake at 350 degrees for 20 minutes.
Using a stand mixer, mix together the Oreos (set 6 cookies aside to use for topping) and cream cheese. Beat for 2-3 minutes until all of the cookies have been completely blended in to the cream cheese to make a smooth truffle texture. Add in 2 tablespoons of sprinkles and mix well.
When the shortbread comes out of the oven, allow it to sit for 2 minutes, then press the truffle filling onto the top of the shortbread evenly. Let this cool for 15 minutes.
Spread the vanilla frosting on top of the truffle layer. You can use as much of the frosting as you'd like. We used about 3/4 of a tub of frosting.
Chop the reserved Oreos and sprinkle them on top of the frosting. Also sprinkle the rest of the colored sprinkles over top of the frosting. Refrigerate the bars for two hours to allow them to set.
Cut the bars and store them in an airtight container.