Make the cookie dough:
In a stand mixer fitted with the paddle attachment, beat together butter, sugar, and cinnamon on medium speed until smooth and fluffy, about 3-4 minutes. Scrape down the sides occasionally.
Add egg and vanilla extract, and beat until combined, about 1 minute.
In a separate bowl, whisk together the all-purpose flour, almond flour, and salt.
Gradually add the flour mixture to the butter mixture and mix briefly until just incorporated.

Chill the dough:
Divide the dough in half and shape each half into a disc. Wrap in plastic and refrigerate for at least 1 hour or up to 5 days.

Roll the dough:
Roll out one disc between two pieces of parchment paper to about 1/4-inch thick.
Using a Linzer cutter or a 2-inch round cutter, cut 12 rounds for the bottoms.
Transfer the bottom cookies to a parchment-lined baking sheet and refrigerate for 30 minutes.
Gather the dough scraps, roll out, and cut more cookies.

Cut the tops:
Roll out the second disc and use the Linzer cutter with the insert or a 2-inch round cutter with a 1-inch cutter for the center.
Place these top cookies on another lined baking sheet and refrigerate for 30 minutes.

Preheat oven:
Preheat the oven to 350°F (175°C) for at least 15 minutes.

Bake the cookies:
Bake the cookies for 8-10 minutes, or until the edges are lightly golden brown. Allow them to cool slightly before transferring to a wire rack to cool completely.

Dust the cookies:
Dust the top cookies with confectioners’ sugar.

Fill with dulce de leche:
Turn the bottom cookies flat side up and spread about 1 teaspoon of dulce de leche in the center.
Top with the dusted top cookies and serve!