Let's preheat the oven to 350F. Line your favorite 8x8 baking dish with parchment paper leaving an overhang on each side.
Mix cookie dough with two tablespoons of holiday sprinkles. Press dough into prepared pan in an even layer. Back 25-30 mins until golden. Allow to completely cool in a pan before removing and cutting.
Spread frosting over a cooled cookie using an offset spatula or butter knife. Sprinkle remaining two tablespoons of colorful sprinkles over the top of the cookie bars! Now cut into 16 even squares.