1Preheat the oven to 120 degrees Celsius.
2Place the hazelnuts on a baking tray and toast them until golden. Once cooled, pulse in a food processor until finely ground.
3In a bowl, beat the butter and sugar together until mixed.
4Add the ground hazelnuts, salt, coffee, and seeds scraped from the vanilla bean to the bowl. Mix well.
5Add in the sifted flour and mix until the mixture starts to pull away from the walls of the bowl.
6Refrigerate the dough for 30 minutes.
7Preheat the oven to 190 C. (or 170 C. if using a convection oven).
8Set the dough on a lightly floured work surface and roll it out, but not too thin.
9Using a cookie cutter or glass, cut out the cookies and transfer them onto a baking tray lined with parchment paper. Leave room between the cookies, as they will expand while baking.
10Bake for 13 to 15 minutes then transfer the whole paper to a baking rack to cool.
11When the cookies are cool, you can optionally glaze them with some chocolate. Just put the chocolate chunks in a microwave-safe bowl and microwave in 1-minute increments until melted.
12Transfer the chocolate into a plastic bag and barely cut off the tip. Squeeze the chocolate back and forth across the cookies.