Via: Šárka Babická
Warm the milk in a small saucepan until tepid. Sprinkle in the yeast and stir well.
Sift the flour and a pinch of sea salt into a mixing bowl. Add the sugar, yeasty milk mixture and both eggs and mix thoroughly by hand. Knead in the butter, one piece at a time. The result should be a soft and elastic dough with a sticky consistency.
Dust the work surface with flour. Lightly grease your hands with a few drops of the oil, then remove the dough from the bowl and shape it into a tight, smooth ball. Lightly grease the mixing bowl and return the dough ball to the bowl. Cover with a tea towel and leave in a warm place to rise for 1-2 hours until it has doubled in size.
Tip the dough out on to a lightly floured surface and knock it back to deflate it, then knead it for 5 minutes, during which time it should become less sticky and more silky. Grease the bowl again and return the dough to the bowl. Cover and leave to rise in a warm place for another 1 hour or until it doubles in size again.
Lightly dust the work surface with flour again. Remove the dough from the mixing bowl and cut it into eight even-sized pieces, then roll each one into a ball. Working with one ball at time, and covering the others with a damp cloth while you work, flatten each ball and brush each one with ½ tsp of the tahini, then sprinkle about 5g of the chocolate chips in the centre. Working with one ball at a time, gather the edges of the dough over the tahini and chocolate, pinching them together into pouches to seal the filling in tightly. Transfer to a non-stick 2lb loaf pan and repeat with the remaining balls. Cover and set aside for 1 hour or until they have doubled in size.
Shortly before the balls have fully risen, preheat the oven to 180˚C/gas mark 4. In a mixing bowl, whisk the egg yolk with 1 tbsp water and the pinch of sugar to create an egg wash, then brush this over the top of the dough balls.
Bake in the oven for 35-45 minutes until the top is golden brown and a skewer inserted in the middle comes out clean. Remove the brioche from the oven and leave it to stand for 5 minutes before turning it out on to a wire rack to cool. When completely cold, cut into slices.