Boil the pasta

• Bring a large pot of salted water to a boil.
• Cook the rigatoni until al dente, then drain, reserving a little pasta water.

Chop the vegetables

• Finely chop the onion and mince the garlic.

Start the spicy base

• Heat the olive oil in a pan and soften the onion.
• Add the garlic, tomato paste and chili flakes and cook until fragrant.

Make it creamy

• Pour in the heavy cream and stir to combine.
• Add the butter and grated parmesan and season with salt and pepper.

Toss and serve

• Add the drained rigatoni to the sauce and toss, loosening with pasta water.
• Serve hot with extra parmesan.