* In a bowl, combine flour, sugar, vanilla sugar, and salt.

3. Combine Wet Ingredients:
* Add the milk-yeast mixture to the dry ingredients.

4. Knead Dough:
* Mix gently, then add the beaten egg.
* After 3 minutes, incorporate the soft butter.
* Knead for 10-15 minutes until the dough is soft but not sticky.

5. First Rise:
* Shape the dough into a ball and let it rise until doubled in size (about 1.5 hours).

6. Shape Dough:
* Degas the dough and shape into 20g balls or roll out to 1cm thick and cut with a cookie cutter.

7. Second Rise:
* Place dough balls on baking paper.
* Cover with tea towel and let rise until doubled in size (about 1 hour).

8. Fry Doughnuts:
* Heat oil to medium temperature (about 160°C).
* Fry until golden on both sides.

9. Finish:
* Coat hot donuts in sugar, or wait until cool to dust with icing sugar.
* Fill with cream or jam if desired.