Ingredients
Scale
**For the Cookie Bars:**
- ¾ cup salted butter (melted)
- 1 cup light brown sugar
- ⅓ cup granulated sugar
- 1 tbsp vanilla extract
- 2 eggs (room temperature)
- 2 cups all-purpose flour
- 1 tbsp cornstarch
- ½ tsp baking soda
- ½ tsp salt
- 1 cup red (white, and blue M&Ms)
- ½ cup red (white, and blue sprinkles)
- ¾ cup milk chocolate chips
**For the Frosting:**
- ¾ cup salted butter (room temperature)
- 4 cups powdered sugar
- 1 tsp vanilla extract
- 3-5 tbsp heavy cream or milk (room temperature)
- ½ tsp salt
Instructions
**For the Cookie Bars:**
- Preheat the oven to 350°F. Grease a metal 9×13 pan and set aside.
- In a stand mixer, combine melted butter, brown sugar, and granulated sugar. Mix until combined. Add vanilla and eggs, and mix until incorporated.
- On low speed, add flour, salt, cornstarch, and baking soda. Mix until just combined. Fold in M&Ms, chocolate chips, and sprinkles.
- Spread batter evenly in the prepared pan. Bake for 22-25 minutes, or until the edges are golden brown. Remove from the oven and cool completely before frosting.
**For the Frosting:**
- In a stand mixer, beat together butter and powdered sugar for 2-3 minutes until combined. Add vanilla, salt, and 2 tablespoons of heavy cream, and beat until smooth. Adjust the consistency with more heavy cream as needed.
- Divide frosting into 3 bowls. Add a few drops of red food coloring to one bowl, blue to another, and leave the third white.
- Pipe alternating colors around the edges using a piping bag with a large tip (like Wilton #8B). Top with additional sprinkles.
- Slice and serve!