In a mixing bowl, cream together the butter and sugar until light and fluffy, about 3-5 minutes. Add in the egg yolks one at a time and mix well. Incorporate vanilla extract.

In a separate bowl, sift together self-rising flour and cornstarch. If using, sprinkle in fresh aniseed and whisk gently.

Gradually fold the dry ingredients into the butter mixture until just combined. Gather the dough into a ball, wrap in plastic wrap, and refrigerate for 10 minutes.

On a floured surface, roll out the dough to about ½ inch thickness and cut out 3-inch circles. Place on a baking sheet lined with parchment paper.

Preheat oven to 350°F. Bake cookies for about 20 minutes until lightly golden. Cool on tray for 10 minutes before transferring to a wire rack.

Spread a layer of manjar blanco on half of the cooled cookies and top with the remaining cookies. Dust with powdered sugar before serving.