For the dough, melt the butter with the warm milk and put aside. Place the flour, yeast, salt, sugar, cardamom and orange zest into a bowl and mix together. Add in the beaten egg and milk mixture and mix together to form a dough. Knead for 10 minutes till smooth then place into a clean bowl, cover and allow to prove for 40-50 minutes.  Meanwhile, melt together the chocolate and hazelnut cream, butter, sugar and spices. When the dough has proved, knock out the air and roll out into a large rectangle. Spread over the chocolate mixture and roll up tightly. Cut down the centre and plait the 2 pieces into a long loaf. Brush with butter and allow to prove again. Bake in the oven at 200°C for 35-40 minutes. Allow to cool. Melt 100g chocolate and chop the remaining 50g. Drizzle the melted chocolate over the plait and sprinkle over the chopped chocolate and broken hazelnuts.