In a large frying pan containing a light covering of olive oil, add the butter, and when melted add crushed garlic. Then add the finely chopped red onion, and when it has softened enough, add the chopped tomatoes, tomato puree, caster sugar, and dried oregano.
Finally when almost cooked add the remaining olive oil, and freshly chopped basil. Then let it cool before spreading the mixture over the pizza crust.
Note: This is my own personal recipe that I'm experimenting with.