Heat oil in a large non-stick frypan over medium-low heat. Add garlic and chilli flakes, and cook, stirring occasionally, for 10 minutes or until garlic is softened and lightly coloured. Cook spaghetti in boiling salted water to packet instructions. Drain, reserving 1/3 cup (80ml) cooking water. Stir pasta and cooking water into garlic mixture, then add parsley and lemon juice. Season then serve immediately.