Simmer the onion and garlic in the olive oil over moderate heat until lightly golden and translucent.
Add the tomatoes, paste, oregano, stock and basil leaves. Simmer for 15 minutes.
This is when the baby tomatoes can be roasted until blistered and squishy. Also, get a pot of salted water on the boil for the spaghetti.
Season with salt, pepper and sugar and simmer for another 10 minutes.
Boil the spaghetti until al dente.
I like my sauce chunky, but feel free to puree with a stick blender for a smooth sauce. Check seasoning.
Using a pasta ladle, add the spaghetti to the sauce and mix until evenly combined. Add a splash of pasta water to allow the sauce to bind to the pasta. Season one more time.
Serve immediately, topped with torn mozzarella, grated parmesan, roasted baby tomatoes and fresh basil.
And a drizzle of extra virgin olive oil for luck.