Layer any flavor of red jello, a layer of blue jello, and the layer in the middle is made by preparing a small box of lemon jello, put it in a bowl in the fridge until it thickens slightly and then fold (gently mix) in a tub of Cool Whip.
red white blue rice crispie treats I made 1 batch for each layer. Spray pan and press each layer with your hands (when cooled). I add the food coloring to the melted marshmallows, makes colors look more even. Then add Rice Krispies.