Chocolate babka

Method

1. Gently warm the milk and 40g of the butter in a small saucepan until the butter has melted – don’t let it boil. Put the flours, salt, sugar and yeast in the bowl of a stand mixer and mix until just combined. Make a well in the centre, then pour the warmed milk and one of the beaten eggs into the bowl. Mix with a wooden spoon until just combined.
2. Mix at medium speed with the dough hook for 15 minutes until smooth. The dough will seem very wet before mixing but will stiffen up when kneaded.
3. Turn the speed up slightly and add the remaining butter, a tablespoon at a time, making sure each addition is incorporated into the dough before adding the next. Mix for 5 minutes until the dough is smooth and slightly sticky. Cover the bowl with cling film and leave to rise at room temperature for 45-60 minutes until nearly doubled in size. Chillin the fridge for another 30 minutes.
4. Meanwhile, make the filling. Put the butter and sugar in a small saucepan and gently heat until melted, then add the remaining ingredients and stir until well combined. Remove from the heat and allow to cool until barely warm. It may look a little grainy because of the sugar but that’s fine.
5. Flour the work surface and tip the dough onto it. Sprinkle the dough with flour and roll out to 28cm x 60cm. Keep moving the dough to make sure it doesn’t stick, dusting with extra flour if necessary. Spread the filling over the dough, and roll it up like a Swiss roll along the longer side.
6. Finishing with the seam underneath, cut the dough lengthways down the centre, leaving the halves attached at one end by about 4cm. Twist the two pieces around each other, then lay the dough into the loaf tin, lowering it from one side to the other and back up again in a zig-zag [K], until used up (roughly 4 turns). It doesn’t have to be neat. Cover loosely with cling film and leave in a warm place to prove for about 30 minutes. It has risen enough when your finger leaves a slight indentation when lightly prodded. Heat the oven to 180°C/160°C fan/gas 4.
7. Very gently brush the top of the loaf with the remaining beaten egg, then bake for 50-60 minutes, loosely covering with foil after 25 minutes. Leave to cool in the tin for 10 min, then turn out onto a wire rack and leave to cool completely.