Mix yeast and sugar in a deep bowl, add water and whisk.
Add 100 ml of flour to the cup, stir with a whisk. The consistency should be like thick sour cream. Leave for 15 minutes for the dough to rise.
Add salt, butter and remaining flour to the cup and knead the dough. It should stick to your hands a little.
Place the dough in a cup and cover with a towel, place in a warm place for 1 hour to rise.
Preheat the oven to 220°C and bake the bread for 15 minutes until browned.
Reduce temperature to 180°C and bake for 45 minutes.
Let the bread cool for 1 hour before serving.