Preheat oven to 350°F (175°C) and lightly grease a 12-inch pizza pan or line a rimmed baking sheet.
Whisk the flour, cornstarch, baking soda, and salt together.
Beat the butter and both sugars until creamy, about 3 minutes.
Beat in the egg, egg yolk, and vanilla.
Mix in the dry ingredients on low until just combined, then stir in the chocolate chips.
Press the dough into a round about 3/4 inch thick on the pan, leaving a 1-inch border.
Bake for 20-24 minutes until puffed and lightly golden, with the center still slightly soft.
Cool on the pan for 15 minutes to serve warm, or about 1 hour before frosting.