1. In a stand mixer fitted with the paddle attachment, beat the softened butter, sugar, and cinnamon on medium speed until smooth and fluffy, about 3-4 minutes. Scrape down the sides as needed.

2. Add the egg yolk and vanilla extract; beat until combined, approximately 1 minute.

3. In a separate bowl, whisk together the all-purpose flour, almond flour, and salt.

4. Gradually add the dry ingredients to the butter mixture, mixing just until incorporated.

5. Divide the dough into two portions, wrap each in plastic wrap, and refrigerate for at least 1 hour.

6. Preheat the oven to 350°F (175°C). Line baking sheets with parchment paper.

7. On a lightly floured surface, roll out one portion of dough to about 1/8-inch thickness. Cut out cookies using a round cutter. Use a smaller cutter to cut out centers from half of the cookies.

8. Place cookies on prepared baking sheets and bake for 10-12 minutes, or until edges are lightly golden. Cool completely on wire racks.

9. Spread about 1/2 teaspoon of dulce de leche on the flat side of each whole cookie. Top with a cut-out cookie, pressing gently to sandwich.

10. Dust the assembled cookies with confectioners’ sugar before serving.