1. Heat the oil in a frying pan or skillet over medium heat. Add the garlic and cook for 1-2 minutes until lightly browned.
2. Add the basil. Stir for 1 minute, then add the tomatoes and their juice.
3. Reduce heat to low and simmer, stirring occasionally, for 5-10 minutes until a sauce-like consistency.
4. Drain the oil from the tuna (not down the sink, though) and add to the pan, breaking it up and mixing it through the sauce. Simmer for 5 minutes.
5. Bring a large pan of salted water to the boil. Add the spaghetti and cook following packet directions or until al dente. Drain and transfer to a warm serving bowl.
6. Stir in the sauce, season with black pepper and basil and serve immediately.