Heat the oven to 180℃

Toss the sprouts with a little oil and season with salt and pepper. Place them in a roasting tray and roast for about 15-20 minutes until they are tender and turning golden brown.

Melt the butter in a saucepan over a medium heat, then add the flour and mix to make a paste. Cook for 2 minutes.

Gradually pour in the milk, whisking continuously, until you have a smooth sauce. Cook until it has thickened slightly.

Add the mustard and the cheese. Mix until the cheese has melted. Take it off the heat.

Place the pancetta lardons into a cold pan with no oil. Cook on a high heat until it has turned crispy. Use a slotted spoon to take the pancetta out, and set it aside. Keep the fat in the pan.

Fry the breadcrumbs in the pan, it will soak up the fat from the pancetta and start to turn crispy.

When the sprouts are nicely golden, toss them with the crispy pancetta and place into an oven proof dish.

Spoon the cheese sauce over, and then sprinkle the breadcrumbs over the whole thing.

Bake for 12-15 minutes, until it is piping hot and bubbling.