In a large mixing bowl, beat together the butter and sugar until pale and creamy.
Add the flour and hazelnuts and switching to the rubber spatula, mix until it starts to form a dough.
Tip out onto a lightly floured surface and knead gently until it comes together.
Form a log with the dough and lay onto a sheet of baking paper. Wrap the dough by rolling the paper onto it, pressing into the dough while rolling to form a long round log.
Twist the end pieces of the paper tightly to close and help keep a round shape.
Allow to rest in the fridge for at least an hour.
Preheat the oven to 170°c(340°f) or 160°c(320°f) if fan assisted.
Take the shortbread log and cut into pieces and place onto a lined flat baking tray.
Bake for 12-15 minutes until the edges start to turn a light golden brown.
Allow to cool fully before dipping in melted milk chocolate. Sprinkle some chopped hazelnuts on while the chocolate is still wet.