Heat the oil in a large non stick pot over medium high heat and add the onion and garlic. Cook for 10 minutes until the onions are golden brown.
Stir in the oregano, basil and salt and pepper, cook for a further minute.
Stir in the tomatoes and puree and cook over a low heat for 10 - 15 minutes.
Boil spaghetti according to pack instructions and add to the tomato mixture with 3 tbsp of the cooking liquid. Add the spinach and mix it all together.
Divide between bowls and swerve with a little parmesan and mozzarella.