STEP 1: PREHEAT THE OVEN

Start by preheating your oven to 350°F (175°C). This ensures that your cookies bake evenly and develop a lovely golden color.

STEP 2: MAKE THE COOKIE DOUGH

In a medium bowl, whisk together the flour, baking soda, and salt. Set this mixture aside. In a large mixing bowl, use a hand mixer or stand mixer to cream the softened butter, brown sugar, and granulated sugar until light and fluffy—about 2-3 minutes. This step is crucial as it incorporates air into the mixture, helping the cookies achieve a chewy texture.

Once the mixture is creamy, add the egg and vanilla extract, mixing until fully combined. Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix, as this can lead to tough cookies. The dough should be soft but not sticky.

STEP 3: PREPARE THE CINNAMON FILLING

In a small bowl, combine the packed brown sugar and ground cinnamon. Stir in the melted butter until the mixture resembles a paste. This filling will create that delicious gooey center in your cookies.

STEP 4: ASSEMBLE THE COOKIES

To assemble the cookies, take a small ball of dough (about 1 tablespoon) and flatten it in the palm of your hand. Place about 1 teaspoon of the cinnamon filling in the center, then fold the edges of the dough over the filling, pinching to seal it completely. Roll it gently between your palms to form a smooth ball. Repeat this process until all the dough and filling are used up, placing the cookie balls on a baking sheet lined with parchment paper, spaced about 2 inches apart.

STEP 5: BAKE THE COOKIES

Once the baking sheet is filled, place it in the preheated oven and bake for 12-15 minutes, or until the edges are lightly golden. The centers may look slightly underbaked, but they will continue to set as they cool. Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.

STEP 6: MAKE THE ICING

While the cookies are cooling, prepare the icing. In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth. The consistency should be pourable but not too runny. If it’s too thick, add a little more milk; if it’s too thin, add a bit more powdered sugar.

STEP 7: DRIZZLE THE ICING

Once the cookies are completely cool, drizzle the icing over the tops using a spoon or a piping bag for more control. Allow the icing to set for a few minutes before serving.