Smash and peel your garlic cloves and add to a pot with roughly 100ml of olive oil. Chuck in the basil stems plus a handful of leaves, saving some for later. Place the pan over medium heat and let it lazily simmer for 1-2 mins. Turn off the heat and allow the mixture to steep while your start your sauce.

Add your butter to a large saucepan, place over a medium heat to melt. Meanwhile, halve your onion and add it, cut-side down, to the pan. As the butter starts to brown, the onion will begin to caramelise.

Add the tomatoes to the pan, breaking them down with a wooden spoon. Bring to a boil, add salt and pepper, pop a lid on and simmer for 20 mins.

Meanwhile, add your steeped oil mixture to a food processor and pulse until the garlic and basil are finely chopped. Set aside.

Bring a large pan of water to a rolling boil, season generously with salt.

When the sauce has simmered away, add the garlic and basil oil and stir until thoroughly mixed. Continue simmering for another 10 mins or so, until the sauce has thickened. Remove and discard the onion halves.

Drop your spaghetti into the boiling water and cook for 8-9 mins until al dente.

Toss through cooked spaghetti with a splash of pasta water until the pasta is beautifully coated. Serve family style topped with a handful of parmesan and extra basil leaves.