The Kitchn: How to make soft, chewy oatmeal chocolate chip cookies
8 tablespoons (1 stick) unsalted butter
1 cup all-purpose flour
2 tablespoons cornstarch
1 teaspoon baking powder
1 teaspoon ground cinnamon
1/2 teaspoon kosher salt
1 cup packed light brown sugar
1/4 cup granulated sugar
1 large egg
1 teaspoon vanilla extract
...continued