Heat 1 tbsp olive oil and butter in a large pan, and cook the onion, pancetta, carrots, celery and garlic for 10 minutes. Add the minced pork and cook until browned. Scatter with flour and cook through for 2 minutes, then add tomato passata, tomato paste, oregano, sea salt, pepper, parsley and 300 millilitres of water, stirring well. Simmer gently for 45 minutes, stirring occasionally until thickened.

Heat the oven to 180C. Cook the pasta shells in boiling salted water according to packet instructions until just tender, then scoop out and rinse under cold water. Cook the peas in the hot pasta water for 1 minute, then drain. Toss the shells in the remaining olive oil.

Spoon ragu into each shell and arrange in lightly oiled baking tray. Scatter with peas and spoon an extra ladleful of ragu over the top. Gently heat the cream, most of the parmesan, lemon zest, nutmeg, sea salt and pepper in a small pan and pour over top. Scatter with remaining parmesan and bake for 20 minutes or until golden and bubbling.