M & M Cookie Bars Soft chewy brown sugar M & M blondie cookie bars. The best M & M Cookie Bars recipe!
Preheat oven to 350 degrees. Melt 1/2 cup of butter (1 stick) in a saucepan over medium-low heat. Let it completely melt and start to bubble. Remove from heat.
In a large mixing bowl, combine the remaining 1/2 cup of butter (1 stick), brown sugar, and sugar. Using a stand mixer or handheld mixer, mix for 2 minutes or until light and fluffy. Carefully add the melted butter and continue to mix for 3 minutes longer.
Add egg, egg yolk, and vanilla and mix for 1 minute.
Fold in flour, baking soda, and salt. Add chocolate chips and M & M's.
Place a piece of parchment paper in a 9 x 13 pan. Press around the sides. Spread cookie dough into baking pan. Bake for 22-25 minutes. Remove from the oven and let set up for at least 15 minutes before cutting into bars.