For the biscuit, separate the whites from the yolks. Whisk the yolks with 100 g of sugar and white vanilla. Add the sifted flour and whisk finely. speed. Separately, whisk the proteins with 50 g of sugar until thick peaks form. Gently mix with a spatula. Also, gently stirring with a spatula from the edge to the center, add the melted and cooled butter.