1-Mix the cinnamon sugar filling: by combining 4 tablespoons softened unsalted butter, 1/3 cup packed brown sugar, 1 1/2 tablespoons all-purpose flour, 2 1/2 teaspoons ground cinnamon, and a pinch of salt. Chill this mixture in the freezer for about 10 minutes to make it easier to handle.

2-For the cookie dough: beat 1 cup unsalted butter (softened but cool) and 1 1/3 cups granulated sugar until light and creamy. Then, add 1 3/4 teaspoons pure vanilla extract, 1 large egg, and 1 large egg yolk, mixing until fully incorporated.

3-In a separate bowl: combine the dry ingredients: 2 3/4 cups all-purpose flour, 3/4 teaspoon baking powder, 1 teaspoon cornstarch, and 1/4 teaspoon salt.

4-Gradually mix the dry ingredients: into the wet mixture to form a smooth dough. Spread half the dough at the bottom of the mixing bowl, top with half the cinnamon filling in small spoonfuls, then layer with the remaining dough and sprinkle the rest of the cinnamon filling on top.

5-Gently fold the layered dough: two times and stir one or two times by hand to keep the chunks and swirls intact, creating those beautiful cinnamon patterns.

6-Scoop the dough: into two-tablespoon portions, making sure to include some cinnamon mixture in each. Place them on a plate and freeze for 10 minutes to prevent spreading during baking.

7-Arrange the dough balls: on the prepared baking sheets, spaced a couple inches apart. Shape them as desired and bake for 10-12 minutes until the edges brown slightly and the centers are just set.

8-Allow the cookies to cool: on wire racks to firm up, which helps them hold their shape and enhances the flavors. Pair them with a simple no-churn ice cream recipe for an extra treat.