Bring a large pot of lightly salted water to a rolling boil and cook the spaghetti according to package instructions until al dente; reserve 1 cup of the cooking water before draining.
While the pasta cooks, finely chop the red chili (de-seeded), mince the garlic with the germ removed, and finely chop the parsley.
In a large bowl, pour in the extra-virgin olive oil, add the chopped garlic and chili, season with salt and pepper, and whisk briefly with a fork to combine.
Add the hot drained spaghetti to the bowl with the oil, garlic and chili; toss to coat evenly.
Add the grated Pecorino and two spoonfuls of reserved pasta water, then mix vigorously until the cheese and water form a creamy sauce; add more pasta water as needed to reach a silky consistency.
Fold in the chopped parsley, toasted pine nuts, toasted slivered almonds and toasted breadcrumbs (if using), adjust seasoning, and serve immediately.