Ingredients
Pan sizes, times and temperatures in the method are not scaled.
Dough
Cocoa-rum filling
Method
Shells
Dough. Cut the cold butter (125 g½ cup + 1 tbsp) into the flour (250 g2 cups) until sandy. Add the egg yolks (2), powdered sugar (50 g7 tbsp), vanilla (1 tsp), zest and salt and press together into a dough without kneading. Chill 30 minutes.
Fill the mold. Grease the walnut mold lightly. Press a small piece of dough into each cavity so it lines the cavity thinly and evenly rather than filling it. Close the mold.
Bake. Set the mold over medium heat on the stovetop, or bake it at 350°F (180°C) if it is oven-safe. Cook 3 to 5 minutes per side, flipping the mold, until golden. Open carefully; the shells should release easily. Cool completely.
Filling and assembly
Filling. Beat the unsalted butter (150 g⅔ cup) with the powdered sugar (100 g¾ cup + 1 tbsp) until fluffy. Add the cocoa powder (16 g3 tbsp), rum (2 tbsp) and vanilla (1 tsp) and beat until smooth and pipeable.
Pipe or spoon filling into one shell half and press a second half on top to make a walnut shape.
Notes
- No mold. Shape the dough over the back of a mini muffin pan to make half-spheres instead.
- The mold has 12 to 24 cavities. Search for "forma de nuci" or "walnut cookie mold".
- Other fillings. Caramel (dulce de leche, made by boiling a can of condensed milk for 2 hours) or vanilla buttercream.