These cookie bars are easy to put together and take with you to BBQs, picnics or just to enjoy at home!
Preheat oven to 325 degrees F. Line a 9x13 pan with tin foil and spray with cooking spray.
Cream butter and sugar until light and fluffy.
Add eggs and vanilla. Beat well.
Add flour, milk and powdered sugar. Start with 1 Tbsp milk. Mix well.
Divide batter evenly into 3 bowls. Add a few drops of food coloring to two of the bowls and mix together until there are no streaks and it is the color you want.
Drop the different colors of batter randomly into the pan. Use the back of a spoon or silicone spatula to spread it out and carefully swirl the batter. Don't do too much or you'll end up with a muddy color.
Bake for 22-25 minutes or until the edges are slightly brown.
Remove and let cool before slicing and putting sprinkles on top.