Directions:

In a mixing bowl, whisk together flour, cornstarch, baking powder and salt, set aside. 

Mix together butter and sugar on medium speed until creamy, about 30 seconds. 

Add in egg yolks one at a time, then add in vanilla extract.

With mixer set on low speed, slowly add in dry ingredients and mix until combined and dough starts to come together**. 

Shape dough into a ball, cover ball with plastic wrap then refrigerate 30 minutes to 1 hour.

Preheat your oven to 350 degrees.

Roll half the dough out onto a lightly floured surface to about 3/16" thick. 

Using a 2" round cookie cutter, cut dough into circles then transfer cookies to a parchment paper lined pan.

Bake in preheated oven for 10 to 11 minutes, then cool for 5 minutes on the pan and transfer to a wire rack.  

Cool completely then spread Dulce de Leche on one side of one cookie, then sandwich to another cookie.

Roll in fine coconut if desired. Enjoy!

**Dough will seem dry and crumbly at first but keep mixing and it should come together well. If not you can mix in a teaspoon or two of milk to bind.