Funfetti Skillet Cookie Also known as pizookie or pizza cookie, it's a ginormous crispy, chewy, sugar cookie filled with rainbow sprinkles of fun. 8 servings 1/2 cup unsalted butter, softened 3/4 cup granulated sugar 1 large egg 1 egg yolk 2 teaspoons vanilla extract 1 1/2 cups all-purpose flour 1/4 teaspoon salt 1 teaspoon baking powder 1/2 teaspoon baking soda 1 1/2 teaspoons cornstarch 2/3 cup white chocolate chips 1/2 cup rainbow sprinkles