Mix the flour, egg, sugar and salt in a bow. Add the yeast and the milk and mix well.
Add the butter and continue working the dough for 5 minutes.
Place a baking towel on the bowl and let the dough rest for 1 hour.
Butter a round baking form and por the dough in the form. Let it rest 30 more minutes.
Cut the nuts and mix with the crème fraiche, sugar and cinnamon powder.
Make holes in the dough and pour the filling in the holes and on the top of the cake. Let it rest 30 minutes. Sprinkle the vanilla sugar all over the cake.
Preheat the oven at 180 degrees Celsius. Place the cake in the oven for 45 minutes.