INGREDIENTS
1 cup
unsalted butter, softened
1 cup
granulated sugar
1 cup
light brown sugar, packed
2
large eggs
1
large egg yolk
2 tsp
vanilla extract
3 cups
all-purpose flour
1 tsp
baking soda
1 tsp
cornstarch
1 tsp
kosher salt
1 1/2 cups
semi-sweet chocolate chips
1 1/2 cups
M&M's candies (any color or variety)