Name: Chocolate M&M Cookie Bars
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Yield: 12 squares
Ingredients: 1/2 cup unsalted butter (melted, 1 stick); 1/4 cup granulated sugar; 3/4 cup packed light brown sugar; 1 large egg (room temperature); 1/2 teaspoon pure vanilla extract; 1.75 cup all-purpose flour; 1/4 cup unsweetened cocoa powder; 1 teaspoon baking soda; 1/2 teaspoon salt; 1 Tablespoon cornstarch; 1 cup semi-sweet chocolate chips; 1/2 cup chocolate M&M's