1. Make the cinnamon filling by beating softened butter, brown sugar, cinnamon, and salt until pale and fluffy, about 2 to 3 minutes.

2. Scoop teaspoon sized balls of filling onto a parchment lined plate and freeze for 15 to 20 minutes until firm.

3. In a large bowl, cream room temperature butter with granulated sugar and brown sugar until light and fluffy, about 3 minutes.

4. Add the egg and vanilla extract, beating until well combined and scraping down the sides as needed.

5. In a separate bowl, whisk together flour, baking powder, and salt.

6. Gradually add dry ingredients to wet ingredients, mixing on low speed until just combined.

7. Remove frozen cinnamon filling from freezer and gently fold into cookie dough with a spatula, using only 2 to 3 folds to keep visible swirls.

8. Scoop dough into 2 tablespoon sized balls and place on a parchment lined baking sheet.

9. Refrigerate dough balls for at least 30 minutes while you preheat oven to 350 degrees F.

10. Arrange chilled dough balls 2 inches apart on prepared baking sheets and bake for 10 to 12 minutes until edges are set but centers look slightly underdone.

11. Let cookies cool on baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

12. Make frosting by beating softened cream cheese until smooth, then adding powdered sugar, vanilla, and milk until drizzling consistency. Drizzle over cooled cookies.