1) Preheat the oven to 200C/Gas 6.
2) Bring a large pot of water to a boil, salt generously, and boil the pasta until al dente, tender but still slightly firm. Drain.
3) In a large bowl, toss the cooked pasta with the marinara sauce, cubed mozzarella pieces, 30g of the Parmesan, black pepper, and the pepper flakes. Transfer the pasta to an oiled 23cm by 33cm baking dish. Cover the top of the pasta with the sliced mozzarella, and sprinkle with the remaining Parmesan. Bake until lightly browned and hot, about 30 minutes. Serve immediately.
For the quick marinara sauce:
2 tbsp extra-virgin olive oil
1/4 medium onion, diced
3 cloves garlic, chopped
800g whole, peeled, canned tomatoes in puree, roughly chopped
Sprig of fresh thyme
Sprig of fresh basil
Freshly ground black pepper
1) Heat the oil in a medium saucepan over medium-high heat. Saute the onion and garlic, stirring, until lightly browned, about 3 minutes. Add the tomatoes and the herb sprigs and bring to a boil. Lower the heat and simmer, covered, for 10 minutes.
2) Remove and discard the herb sprigs. Stir in the salt and season with pepper to taste. Use now, or store covered in the refrigerator for up to 3 days, or freeze for up to 2 months.