Rainbow Cupcakes Ingredients Rainbow Cupcakes 1 cup all purpose flour 1 1/2 tsp baking powder 1/4 tsp salt 1/2 cup sugar 2 large eggs 1/2 cup vegetable oil (or melted butter) 1/2 cup buttermilk 1 tsp vanilla extract red, yellow, green and blue food colorings Quick Buttercream Frosting 1/2 cup butter, room temperature 3