For the Cantuccini, first preheat the oven to 190 °C. Beat the sugar, yolks and eggs with a mixer until creamy and pale. Perfume with orange blossom essence, fold in flour together with baking powder and salt. It should form a malleable dough.
Add almond kernels to the dough. Shape the dough into three rolls the length of the baking sheet, place on a baking sheet lined with parchment paper, spacing them enough apart to allow them to rise. Brush the rolls with beaten egg and bake in the oven for about 15 minutes until light brown.
Let the rolls cool briefly. Then cut diagonally into slices about 2 cm thick. Spread cantuccini evenly with the cut surface not on the baking tray (i.e. standing on the broad side) and bake again for a good 10 minutes.