Put 1 lt of water and the tomato paste into a medium pot and bring to the boil. Cook for 10 minutes over medium heat, then set aside. 

Heat up the extra virgin olive oil in a cast iron or stainless steel large pan, then add the garlic and the chillies,  cook for 30 seconds, or until fragrant. Add the tomato passata, season with salt and pepper and cook for 3-5 minutes, stirring to reduce the sauce slightly. Add the spaghetti in one layer into the pan, coat with the sauce and cook, undisturbed for about 3 minutes to help caramelize the pasta. Use a spatula to roll your pasta over  to start cooking the other side. 

Start adding the tomato water into the pan, 1-2 ladlefuls at a time but try to not move the pasta around too much. Keep adding the tomato water to the pan like you would add stock to risotto. Only stir very gently and occasionally. 

It will look like the pasta is sticking, and that’s what you want. Keep doing this for 8-9 minutes or until the pasta is al dente and most of the tomato water has been absorbed. Taste for seasoning and adjust to taste. Serve into bowls with an extra drizzle of extra virgin olive oil, if liked. Eat straight away!