Sift 350 g all-purpose flour and mix it in a bowl with 35 g sugar and 1 pinch salt.
Carefully warm the 40 ml milk until lukewarm, crumble in the 0.5 cube fresh yeast and stir until it has completely dissolved.
Gradually add the yeast milk to the flour mixture and work it in with the dough hook of a stand mixer.
Add the 3 eggs one at a time and knead them in briefly.
Add the 125 g soft butter to the dough in small pieces while kneading constantly until you have an elastic, smooth dough. Add a little more flour if needed.
Cover the bowl with plastic wrap and let it rise in a warm place for approx. 60 minutes until it has doubled in volume.
In the meantime, grease the muffin pan or pans with butter.
After rising, knead the dough again briefly on a floured work surface.
Divide the dough into 12 portions and place them in the cups of the muffin pan. Cover with a towel and let the dough rise again in a warm place for 30 minutes.
Preheat the oven to 180 °C (350 °F), conventional oven (top and bottom heat).
Whisk the 1 egg yolk with 1 tbsp milk. Brush the egg wash onto the brioches.
Put the brioches in the preheated oven and bake them one batch after another for approx. 15 minutes until golden brown.
After baking, let them cool briefly, turn them out of the pan and let them cool on a wire rack.