Cream together butter and sugar in the bowl of a stand mixer. Add egg, and vanilla and beat.
Add flour, almond flour, and salt. Mix to incorporate. Divide into two equal parts. Shape into disks and flatten. Wrap in plastic wrap. Refrigerate for 2 hours. Roll the first dough into 1/8-inch thickness. Cut dough into rounds using a fluted round cookie cutter. Transfer to a parchment paper lined baking sheet. Gather and Re-roll dough until no more remains. Do the same to the second half of the dough. Use a smaller round cookie cutter smaller than the fluted cutter and cut in the center of the fluted rounds. Place on a second cookie sheet. Refrigerate for 15 minutes. Preheat the oven to 350 F. Bake cookies for 10-12 minutes, until the edges are golden. Cool cookies for 2 minutes on the baking sheet, then transfer to a cooling rack. Dust the smaller cookies with powdered sugar. Then add about 1 tsp of dulce de leche to the bottom of halves and sandwich together with the tops.