Babka

Method

1. Whisk 100 g of strong white flour with 12 g of caster sugar, 1 g of instant yeast and 1 pinch of fine salt in a bowl. Add 1 beaten egg and 30 ml of lukewarm milk and bring together to a shaggy dough with a spatula.
2. Knead on an unfloured worktop for 8 minutes until smooth and elastic, then smear in 12 g of very soft butter a little at a time and keep kneading 5 minutes more; the dough will be slack at first, then pull cleanly from the surface and pass the windowpane test. Round it up, cover the bowl and leave in a warm place for 1 hour 30 minutes, until doubled and puffy.
3. While the dough rises, melt 30 g of chopped dark chocolate with 8 g of butter in a small bowl set over barely simmering water. Off the heat, beat in 6 g of cocoa powder and 15 g of icing sugar to a thick, glossy paste and leave until cool but still spreadable, like soft peanut butter.