1: Place the flour, salt and yeast in a free standing mixer attached with a dough hook. Beat the eggs together in a large jug with the milk, and with the mixer on its lowest speed setting pour the eggs onto the flour in batches. Once all the egg has been added, allow the mixer to knead the dough for 5 minutes.
2: Meanwhile, cream together the butter and the sugar in a mixing bowl using a wooden spoon until creamy. Add this to the dough a little at a time with the machine still on a low setting. Once added, allow the dough to be kneaded for another 5 minutes.
3: Finally, add the chopped chocolate chunks to the dough at the last minute and allow them to be incorporated. Cover the bowl with clingfilm and allow to rise and double in size in a warm place; usually 2 hours.
4: After it has doubled in size, flour your fingers well and punch down the dough, cover again and chill for about 4 hours, or doubled in size. After chilling, grease 2 x 6 bun muffin tins. Turn the dough out onto a lightly floured surface and knead gently for 1 minute. Divide the dough into 12 equal portions and place in the muffin tins. Cover with a plastic bag and allow the dough to rise again for an hour in a warm place.
5: Preheat the oven to gas 6, 200°C, fan 180°C.
6: Brush the brioche dough with the milk and bake for 18-20 minutes until risen and golden brown. Allow to cool a little in the tins before turning out onto a wire rack to cool completely.