1. Cook the spaghetti in lightly salted boiling water for 12 minutes of until just tender. Drain well and keep hot.
2. Add the garlic and tomatoes to the saucepan and bring to the boil. Simmer, uncovered, for 2-3 minutes.
3. Add the tuna, chilli sauce, if using, the olives and spaghetti. Heat well, add the seasoning and serve hot.