Melt the butter in a saucepan over a medium heat until sizzling, then fry the pancetta for 5-6 mins until crisp and golden. Turn the heat down to low, add the black pepper and cook for 2 mins until well toasted. Stir in the flour and cook for 1 min more, then gradually whisk in the milk until smooth. Simmer for 3-4 mins, stirring until thickened.

Meanwhile, cook the macaroni following pack instructions until al dente, then drain. Take the sauce off the heat and stir through the cheddar and half the parmesan until melted and smooth. Taste and season if needed, then mix in the pasta. At the last minute, stir through the mozzarella.

Heat the oven to 200C/180C fan/gas 6 and butter a 25 x 18cm ovenproof dish. Spoon in the pasta and smooth the top. Scatter over the panko crumbs and remaining parmesan, and bake for 25-30 mins until golden and bubbling. Serve with a sharp, green salad, if you like.