Black and White Checkerboard Cookies
Finely chop the chocolate, separately, and refrigerate.
Beat the egg, egg yolks, butter and sugar until fluffy. Stir in the vanilla bean seeds, salt, flour and cornstarch. Divide the dough in half. Mix the cocoa powder and dark chocolate into 1 portion and the white chocolate into the other half.
Transfer the dough to separate pastry bags fitted with medium plain tips. Pipe into lattices on a baking sheet lined with parchment paper and bake in a preheated oven (200°C) (approximately 400°F) for about 10 minutes. Remove from the oven and let cool.