Make the brioche a day before you plan to serve the dish. Place the milk and yeast in the bowl of a stand mixer with a dough hook attached. Add the flour, salt and eggs, then knead at a medium speed for around 10 minutes until smooth and elastic. You can also do this by hand, but it will take longer

Gradually add the butter and sugar with the motor running, then increase the speed and continue working for 10 minutes. Cover the bowl and allow to prove in a warm place for 2 hours, or until doubled in size

Knock back the dough by punching it down a few times, then transfer to a clean container and cover with cling film. Refrigerate overnight

The next day, preheat an oven to 200°C/gas mark 6. Crush the pistachios to a coarse powder in a food processor and beat the eggs with a whisk. Peel the sausage, then dust all over with the flour, tapping off any excess. Roll the sausage in the beaten egg (reserve some beaten egg to wash the dough later), then in the nuts until fully covered

Take half of the brioche dough (the other half can be used to make doughnuts or a separate brioche loaf) and roll it out so that it is slightly longer than the sausage and wide enough to wrap around it with a slight overlap. Place the nut-crusted sausage in the middle and roll in the dough, covering the ends. Pinch together the seam and transfer to a loaf tin seam-side down. Allow to prove in a warm place for 25–30 minutes

While the brioche is proving, prepare the port reduction. Melt the butter in a saucepan and add the shallots. Cook until soft without colour (about 3 minutes), then add the port and red wine. Reduce until syrupy. Add the chicken stock and reduce again until syrupy in texture

Once the brioche has finished proving, brush with some of the beaten egg and bake for 25 minutes. Allow to cool slightly

To serve, slice the brioche into thick pieces. Serve with the port reduction and a bitter leaf salad on the side