Preheat the oven to 200 C. Spread the hazelnuts in a single layer on an ungreased baking tray and bake for 8 to 10 mins until fragrant and golden-brown. Set aside to cool. <br></br>

In a mixing bowl, beat the butter and sugar until smooth and creamy. Mix in the vanilla extract.<br></br>

Add the flour and slowly mix it in.<br></br>

Pulse the hazelnuts in a blender until a few larger bits remain. Mix it into the dough. <i>I prefer doing it this way to get the maximum hazelnut flavour throughout the cookie dough. If you prefer a chunkier dough, simply chop the hazelnuts up by hand.</i><br></br>

Use a cookie scoop (recommended) or your hands to form 10 to 12 equal sized portions of the dough, placing them 1 inch apart on a silicone mat lined baking tray (or just grease the tray). <i>They will flatten in the oven anyway, so I prefer to use a cookie scoop here instead of worrying about making perfect rounds.</i><br></br>

When ready to bake, preheat the oven to 175 C. Slide the tray into the oven and bake for 15 to 20 mins until the bottoms have flattened a little bit, and the tops are lightly browned.<br></br>

Set aside to cool for 5 mins. Spread the sifted, powdered sugar out onto a large, flat plate and roll the still-hot cookies in it, coating them all over. Transfer to a wire wrack to cool completely, then roll one more time and eat the whole batch!<br></br>