Preheat the oven to 350°F (175°C).

In a mixing bowl, combine softened butter and powdered sugar. Beat until light and fluffy.

Mix in egg yolks and vanilla extract until well combined.

In another bowl, whisk together flour, cornstarch, and baking powder.

Gradually add dry ingredients to the wet mixture, stirring until a soft dough forms.

On a lightly floured surface, roll out the dough to about 1/4-inch thickness.

Cut out shapes using a cookie cutter and place them on a baking sheet lined with parchment paper.

Bake for about 15 minutes or until the edges are lightly golden.

Once cooled, spread a layer of dulce de leche on one cookie and top with another.

Dust with powdered sugar before serving.