In a bowl, beat the butter until creamy.

Add the sugar and beat until combined. You can do this by hand or with a mixer. Add vanilla and lemon zest.

Once incorporated, add the egg yolks one at a time, waiting for each to integrate. Finally, add the cornstarch, flour, and baking powder (already sifted), and mix manually until you have a smooth but crumbly dough. Refrigerate for 30 minutes.

Remove from the fridge, divide into two parts, and roll out with a rolling pin to a thickness of about 1/5 inch. Cut into circles about 1 1/2 to 2 inches in diameter.

Grease a baking sheet, place the discs on it, and bake for 15 minutes or until they are slightly golden at the edges.

Let them cool, fill with dulce de leche using a piping bag, and roll in coconut. Enjoy these delicious alfajores from Argentina to the world!