Melt butter and let cool.Mix flour, sugar, salt, vanilla sugar and ground lemon peel. Let the yeast rise in milk, spoon of sugar and bit of flour, pour into the dry mix. Add yolks, whipping cream and at the end melted butter (raisins and nuts if desired). Kneed the dough by hand, dust with flour and let rise at warm place for 1 hour. Make two loaves, place on baking sheet lined with parchment paper and let rise additional 15 min. Brush with egg, with sharp knife cut a cross on top. Bake at 180 C. Brush with egg again after 20 min of baking, sprinkle with shaved almonds and finish baking for another 30 min. Done when toothpick inserted in the middle comes out clean.