Pasta al forno ("baked pasta" or "pasta in the oven") is an Italian casserole made with pasta, creamy tomato sauce and cheese. It may sound fancy and there are lots of variations, yet it couldn't be ...
Gently fry the onion for 4–5 minutes ... Season with a little salt and lots of black pepper. Toss together until the spaghetti is lightly coated in the sauce and serve immediately.