Beat your eggs, honey and vanilla extract together.
Place your flours, salt, yeast and sugar into your stand mixer bowl and stir to ensure thoroughly mixed.
Heat your milk until warm, 10-15 seconds in a microwave should be enough, be sure to use a microwavable container.
Pour a third of your egg mixture into your flour mixture and knead on a low setting until it just starts to mix in, about 20 seconds or so, then add in half of your warm milk and mix again for the same amount of time.
Repeat until all of your egg and milk have been added.
Knead for about 2 minutes on a low setting until all of your flour mixture has been incorporated.
Add a third of your softened butter and knead, again on low, for a minute. You will still have some small lumps of butter remaining after a minute, that's fine.
Repeat with the next 2 lots of your butter, kneading in between each one for a minute on low.
Knead on a medium-high setting (I used setting 2-4 on my KitchenAid) for 8-10 minutes.
The dough is ready once it has an elastic quality to it, and when it is tacky but not overly wet and sticky. It will be wetter than normal bread dough. If you dough is still very wet add 3 tablespoons of flour and continue kneading for another 5 minutes.
Remove the dough from the mixer bowl and place it on a floured surface.
Oil the bowl, to stop the dough from sticking when you replace it, I used olive oil.
Knead the dough a few times, then make it into a ball shape and return it to your oiled bowl, cover the bowl with oiled clingfilm (plastic wrap).
Leave to rise in a warm place for approximately 2 hours. When ready it will have doubled in size, this can take anything between 1-3 hours.
Remove the dough from the bowl and knead 3-4 times.
Return to the bowl (re-oil if needed), cover with the oiled clingfilm (plastic wrap) but this time place in your refrigerator for 4-24 hours. Again it will need to have doubled in size before it is ready.
Grease your loaf tin.
Remove your brioche dough from your bowl and sprinkle over your chopped chocolate, knead the chocolate in a few times until equally mixed in.
Split the dough into 6 equal size balls and then insert the balls into your greased loaf tin.
Leave to rise for 30-45 minutes, the dough is ready when it has risen to just above the edge of the tin.
Preheat your oven to 170°C Fan/190°C/375°F/Gas mark 5
Separate your egg and paint the yolk over the top of your brioche bread using your pastry brush, then bake for 35-40 minutes, the bread is ready when it is a deep golden colour all over and sounds hollow when you remove it and tap the base.
Leave in the tin for 5-10 minutes to cool and then remove and leave to continue cooling on a cooling rack.