Let's get Cooking...

1. In a medium bowl, whisk together the flour, baking soda, cornstarch and salt. Set aside. In a large bowl, mix together the butter with both sugars until creamy. Add egg and vanilla extract.
2. With mixer on low incorporate the flour mixture.
3. Fold the M&Ms by hand.
4. Cover and refrigerate the dough for 30 minutes up to two hours.
5. Preheat oven to 325 F (165 C). Line two baking sheets with parchment paper. Using an ice cream scoop, take equal portions of dough and place on the prepared baking sheets, 1 inch apart.
6. Bake for 15-20 minutes until slightly golden on the edges.
7. Let the cookies cool on the baking sheets until the cookies are firm enough to remove, probably another 5-­10 minutes. Cool completely on a wire rack.