Cream 1-1/2 sticks butter, 1/2 Cup granulated sugar and 1/2 Cup brown sugar. Then add 2 teaspoons vanilla and one egg. Then add 2 Cups flour, 2 Teaspoons corn starch, 1 Teaspoon Baking soda, 1/2 Teaspoon salt. Mix until creamy. Then add M&Ms & chocolate chips. Roll into balls and put in freezer for 15 minutes. Then take out of freezer and bake at 350 degrees for 10-12 minutes. So delicious!