1-Preheat the oven: Preheat the oven to 325°F and spray a standard half sheet pan (13×18 inches) with nonstick spray to prevent sticking.

2-Whisk the melted butter and sugars: Whisk the melted butter and sugars together until smooth, making sure to break up any clumps for an even mix.

3-Add the eggs, milk, and vanilla: Add the eggs, milk, and vanilla, and whisk until everything is fully combined and silky.

4-Add the dry ingredients: Add the dry ingredients flour, cornstarch, baking soda, baking powder, and salt and fold them in until mostly combined, avoiding overmixing.

5-Fold in the chocolate chips: Fold in the chocolate chips just until they are evenly distributed through the dough.

6-Spread the dough evenly: Spread the dough evenly on the prepared baking sheet, pressing it down slightly for uniform thickness, and top with extra chocolate chips if you like.

7-Bake: Bake for about 22 minutes, keeping an eye on them to slightly underbake so they finish cooking as they cool. Once done, cool completely before cutting into squares.