Preheat the oven to 325 degrees F.
Spread the hazelnuts on a baking sheet and toast in the oven until golden brown, about 8 minutes.
Meanwhile, melt the sugar in a hot saucepan over medium-low heat, stirring until dissolved, frequently brushing down the sides of the pan with a wet pastry brush. Increase the heat and let boil until the syrup turns golden brown.
While the sugar is cooking, heat a large pot over medium heat and add the nuts, stirring constantly. Pour the caramel into the hazelnuts, stirring with a wooden spoon until the caramel reaches your desired color. Sprinkle some water onto the nuts to shock them to stop the cooking. Pour the mixture into a single layer onto a clean granite or marble work surface or baking sheet. Constantly move the nuts around so they cool all separated. Transfer to a container and refrigerate until cool.
Melt the chocolate in the microwave or over a double boiler and heat to 90 degrees F. Meanwhile, heat a bowl to room temperature, then place the cold nuts into the bowl. Constantly stir nuts while pouring in the melted chocolate, just enough to coat. Continue to stir, stir, stir. The chocolate should stick to the cold nuts and not to the bowl. Stop stirring when the chocolate starts to stick to the bowl. Transfer to a container and refrigerate again. Repeat this process until the desired nut-chocolate ratio is reached. Let rest for a few hours and then enjoy.
Recipe courtesy of Albert Kirchmayr, Kirchmayr Chocolates, Timonium, MD