INGREDIENTS
1 1/2 sticks
unsalted butter, room temperature
1 cup
brown sugar
1/2 cup
granulated sugar
1
egg, room temperature
1 tbsp
vanilla extract
2 1/2 cups
all-purpose flour
2 tsp
cornstarch
1 tsp
baking soda
1/2 tsp
salt
1
bag semi-sweet chocolate chunks
1 cup
M&Ms (plus more to top the cookie if desired)