Preheat the oven to 350 degrees;;Cream together the butter and sugar. Add in eggs one at a time, mix well in between additions. Then add the honey, vanilla. Mix well, Fold the yogurt into the mixture with a rubber spatula. Then combine the flour, baking powder, salt, cinnamon in a separate bowl. Stir it into the wet ingredients just until combined.Fold in the zucchini and if you are using the chocolate chips and hazelnuts.Divide the batter between 2 greased loaf pans. Place 3 tsp of Nutella on top of each pan of batter. Swirl with a fork. Bake for 50-60 minutes until a toothpick inserted comes out clean. Cool before slicing.