Heat oven to 375º. Mix powdered sugar, butter, vanilla, egg and food colors in large bowl with spoon. Stir in 1 1/4 cups of the Bisquick mix. Shape dough into a ball. Sprinkle remaining 1/4 cup Bisquick mix on countertop or other hard surface. Roll ball of dough in Bisquick mix. Knead dough 10 times.