ready in 2 h. 45 min.
Line 2 baking trays with non-stick baking paper.
Bring the milk to a boil, then remove from the heat and add the butter. Leave to cool until warm to the touch.
Mix together the flour, salt, sugar and yeast in a mixing bowl. Add the warm milk and egg and mix with your hands until it comes together. Don't knead.
Put the dough in a lightly oiled bowl. Cover with oiled cling film and leave to rise in a warm place for about 1 hour until doubled in size.
Heat the oven to 200°C (180° fan) 400°F gas 6.
Add the chocolate chips and mix into the dough. Leave to rise as before for a further 1 hour until doubled in size.
Divide the dough into 15 even sized pieces and roll into balls with oiled hands. Place on the baking trays.
Brush the tops of the buns with egg yolk and bake for about 20 minutes until golden brown. Tap the bottom of a bun - if it sounds hollow it is cooked. Cool on the tray for 5 minutes, then place on a wire rack to cool completely.