Dissolve yeast in lukewarm milk in a large mixing bowl; let stand 5 minutes. Add half of the flour (sieved), the melted butter and spices, beat at low speed with an electric mixer until smooth. Gradually stir in enough remaining flour to make a soft dough. Place dough in a well greased bowl, turning to grease top. Cover and let rise in a warm place for 45 minutes.
Knead rock sugar into the dough. Put dough in a bread backing form and let rest for 15 minutes. Bake in a preheated oven (200°C) for 30 minutes until golden brown. Allow bread to cool down. Roast a few slices of the sugar bread in a toaster.
Mix the powdered sugar with the lemon juice and crème fraiche. Spread the lemon, sugar, crème fraiche mix on the toasted sugar bread and cover with blueberries. Add a spoon of lemon curd to the creme fraiche.