Boil 2 eggs in a small saucepan of water for 9 to 10 minutes for firm yolks. Cool under cold water, peel, and separate yolks from whites, saving the whites for another use.

Push the cooked yolks through a fine-mesh sieve into a small bowl while still warm, breaking them into a fine, sandy crumb.

Heat the oven to 170 C / 340 F and line a 33 x 46 cm / 13 x 18 inch sheet pan with parchment.

In a large bowl, beat the softened butter and sugar together for 2 to 3 minutes until pale and light.

Add the sieved hard-boiled yolks, the raw egg yolk, vanilla, and salt. Beat until smooth and no streaks remain.

Sift the flour and cornmeal together, then fold into the butter mixture in two additions until a soft, cohesive dough forms.

Cover and chill the dough for 20 minutes, until it's firm enough to hold shape but still soft enough to pipe.

Spoon the dough into a piping bag fitted with a large star tip. Pipe 8 cm strips onto the sheet pan, curving each into a C shape and spacing them 3 cm apart.

Bake for 13 to 15 minutes, until the edges are light gold and the centers stay pale.

Cool on the pan for 5 minutes, then transfer to a wire rack to cool completely. Dust with powdered sugar once fully cool, if using.