Put the flour, almonds, hazelnuts, sugar, 1 packet of vanilla sugar, salt, Amaretto egg yolk and espresso in a bowl. Add butter in pieces. Knead with the dough hooks of the hand mixer to a smooth dough. Shape into a ball with your hands. Cover and chill for about 1 hour.
Roll and shape small pieces of dough into croissants on the work surface. Place on two baking trays lined with baking paper. Bake one after the other in a preheated oven (electric: 200 °C/ gas: level 3) for about 10 minutes, so that just the tips turn brown. Crumble the Amarettini very finely. Sift icing sugar. Mix with amarettini and remaining vanillin sugar and sugar crystals. Carefully roll hot croissants in it. Let it cool down on a cake rack. Keep the croissants well closed in tins in a cool place.
Mix with amarettini and remaining vanillin sugar and sugar crystals. Carefully roll hot croissants in it. Let it cool down on a cake rack. Keep the croissants well closed in tins in a cool place. Keep for about 4 weeks. Results in approx. 30 pieces