Sauté the pancetta or bacon in its own fat. Preheat the oven to 190°C/375°F/gas mark 5.
Make a white sauce by melting the butter and stirring in the flour to form a roux.
Cook over a low heat for a couple of minutes, then take off the heat and start adding the wine a little drop at a time, stirring well after each addition to make sure the liquid is well incorporated and the mixture is lump free.
Gradually add the milk in the same way. Return to the heat once all the liquid has been added and bring to the boil, stirring all the time.
The sauce will thicken considerably. Once it’s boiling, reduce the heat and let it simmer for about four minutes to cook the flour.
Add the mustard, seasoning and Parmesan and, once the cheese has melted, the cream (if you’re using it).
Steam or boil the broccoli until it’s just tender. Make sure you drain it well or it will make the sauce watery.
Lay the broccoli in a small gratin dish, season, then top with the chicken and bacon. Pour the sauce over the top and bake in the hot oven for 20 minutes, or until bubbling and golden.
Serve immediately. I like this with rice on the side but potatoes or buttered pasta are good too.