Striped Dark and White Chocolate Cookies
In the bowl of an electric mixer, beat the egg and egg yolks, butter and sugar until light and fluffy. Slit the vanilla bean lengthwise and scrape the seeds into the bowl along with the salt, flour and cornstarch. Stir to combine.
Divide the dough in half. Fold the cocoa, grated dark chocolate and if necessary, a little milk into one half of the dough. Fold the grated white chocolate into the other half of the dough.
Preheat the oven to 200°C (approximately 400°F). Line a baking sheet with parchment paper.
Spoon each dough into a pastry bag fitted with a plain tip. Pipe rows of dark dough and light dough next to each other, so they're touching and bake until the cookies are set, about 20 minutes. Remove from the baking sheet to a wire rack to cool completely.