Chewy Chocolate Chunk Cookies.
3/4 cup (1.5 sticks or 170g) unsalted butter, softened to room temperature,
3/4 cup (150g) dark brown sugar,
1/4 cup (50g) granulated sugar,
1 large egg, at room temperature,
2 teaspoons vanilla extract,
2 cups (250g) all-purpose flour,
2 teaspoons cornstarch (aka cornflour),
1 teaspoon baking soda,
1/2 teaspoon salt,
1 and 1/4 cup (225g) semi-sweet chocolate chips.