In a large bowl, cream the butter, granulated sugar, and brown sugar together until smooth and creamy. Add in the egg, almond extract (if using), and the vanilla extract, and mix to combine.
½ cup butter, ½ cup granulated sugar, 2 tablespoon brown sugar, 1 large egg, 2 teaspoon vanilla extract, ¼ teaspoon almond extract
Mix in the flour, baking powder, salt, and cornstarch just until the flour mixture barely disappears. Spread the batter into the prepared baking pan and bake in the preheated oven for 15 minutes. The center will still look raw but don't worry these bars will continue baking as they cool down.
½ teaspoon baking powder, 1 cup all purpose flour, 3 tablespoon cornstarch, ¼ teaspoon salt