First of all, melt white chocolate in a bowl in a microwave oven. If you don’t have a microwave oven, you can melt the chocolate using a double boiler. Meanwhile, blend wafer cookies in a food processor. Then add hazelnuts, so they will be chopped in bigger pieces. Add the wafer crumbs mixed with hazelnuts, powdered sugar and yogurt to the melted chocolate. Stir the mixture until all ingredients are well combined. Place the dough on a sheet of baking paper and give it the shape of a salami. Wrap it up with baking paper and fold it like a candy. Place the salami in the freezer for al least 2 hours or overnight until fully firm. Once ready, transfer the chocolate salami onto a platter, dust it with icing sugar and cut into slices. Either keep in the fridge for maximum 3-4 days, wrapped in aluminum foil or baking paper, or keep in the freezer for 7-10 days.