Walnut Tartlets: Crisp Cocoa Shells, Rum-Walnut Filling and Chocolate Ganache Rosettes in Bite Size

Instructions

1. Make the dough (a day ahead): Mix all the dry ingredients (flour, powdered sugar, vanilla sugar, cocoa) in a bowl. Add the cold butter and the yolks. Work the dough quickly until it just comes together. Do not knead it for long, or the warm hands will make it greasy and the baked shells rubbery. Wrap it in plastic and refrigerate until the next day.

2. Bake the tartlet shells: Take the rested dough out of the refrigerator. Do not grease the molds, because the dough is buttery enough. Pinch off small pieces of dough and press them with your thumb into small tartlet molds in a thin layer. The dough must follow the shape of the mold and leave a good hollow in the middle for the filling. Bake in an oven preheated to 340°F (170°C) for about 17 minutes. Let cool and pop out the shells (they release by themselves).

3. Start the chocolate cream (ganache): Heat the cream until just below boiling (do not boil). Pour the hot cream over the broken chocolate in a bowl. Let it stand a few minutes so the heat does its work, then stir until smooth. Leave it on the counter at room temperature until it reaches 77 to 86°F (25 to 30°C), about an hour; it must cool but still be liquid.

4. Finish the cream: Add the soft butter to the cooled chocolate mixture and blend smooth with an immersion blender. Chill the cream briefly so it firms up enough to pipe, but check it so it does not set rock hard.

5. Make the filling: Simply mix the ground walnuts, powdered sugar and rum in a bowl. Let it stand a while so the nuts soak up the liquid and the flavors combine.

6. Fill and decorate: Press a small mound of walnut filling into each cooled shell with a spoon or your fingers. Spoon the chocolate cream into a piping bag fitted with a tip (a closed star tip is ideal). Pipe a rosette onto each tartlet in a circular motion.

7. Store: Chill the finished tartlets until firm and keep them in an airtight container in the refrigerator. They taste best after 2 to 3 days, when the flavors have come together.