Get a pot of heavily salted water boiling for the pasta and cook the pasta, timing it to add straight into the sauce at the end. Reserve a mug of pasta water if you drain the pasta before the sauce is ready.

Heat the olive oil and butter in a big frying pan over medium-high heat and add onions.

When sizzling, lower the heat to medium-low and cook for 4-5 minutes until soft.

Add the garlic and black pepper and cook for a further minute or two, ensuring nothing browns.

Add the tomato paste and whisk to combine, cooking for a minute or two.

With the heat still low to medium, add the cream and whisk to combine evenly, keeping the cream at a very gentle simmer.

Add the lemon juice and whisk in quickly.

Add the finely grated parmesan in three separate lots, whisking in between to ensure it melts.

Add the pasta straight into the sauce with a splash of pasta water (about ¼ cup). Let the pasta simmer in the sauce gently for a minute or two to thicken the sauce. Loosen with more pasta water if needed.

Taste for seasoning and add salt to taste.

Serve and enjoy.