Crumble the yeast in a bowl.
Warm the milk to finger temperature and add it on the yeast. Add flour and stir together. Let it rest 15 minutes.
Mix sugar, salt, and vanilla sugar in a bowl. Add the eggs.
Melt the margarine and pour it on the dry ingredients and mix well.
Pour in gradually the flour and milk mixture in the bowl with the margarine and work it to a smooth dough.
Place a plastic film and and a towel on the bowl and place it in the oven with no heat for 1 hour 30 minutes.
Take out the dough from the oven and divide it in 3, and make 3 long rolls approx 30 cm long each.
Form a braid with the 3 rolls, and place the cake on a baking sheet. Let it rest 30 minutes.
Preheat the oven with electrical heat at 180 degrees Celsius.
Mix the egg yellow with 1 tablespoon of milk, and brush the cakes surface. Sprinkle the almond flakes on the cake.
Place the cake in the middle of the oven for 40 minutes.