Pour 500 g of flour into a large bowl, form a dimple in the center and crumble in the brewer's yeast along with a teaspoon of granulated sugar; then slowly add the milk, forming a very soft batter with about half the flour, leaving this yeast mixture surrounded by the remaining flour.

Cover the bowl with a towel and put it in a warm place for about an hour.

Add to the risen dough a pinch of salt, the melted and warm butter, the 4 egg yolks, two tablespoons of granulated sugar and the surrounding flour. Work it energetically until the dough pulls away from your hands and the bowl.

Form 26 equal balls that you will place between two sheets and let them rise for at least 2 hours.

Fry them in hot oil, but not too much so that the dough can cook perfectly on the inside as well: drain the Krapfen and lay them on white kitchen paper so they absorb the grease.

Sprinkle them with powdered sugar and serve warm.