Gather ingredients: spaghetti, salt, olive oil (optional), minced garlic (optional), crushed tomatoes or marinara sauce, onion (optional), ground beef or Italian sausage (optional), olive oil, dried oregano, dried basil, black pepper, red pepper flakes (optional), grated Parmesan (optional)
Bring a large pot of water to a boil
Salt the boiling water generously
Add spaghetti and stir immediately to prevent sticking
Cook until al dente, stirring occasionally
Reserve 1 to 2 cups of pasta water
Drain spaghetti
Heat olive oil in a large pan (optional)
Sauté chopped onion until softened (optional)
Add garlic and cook briefly until fragrant (optional)
Brown ground meat if using, then drain excess fat if needed (optional)
Stir in crushed tomatoes or marinara sauce
Season with oregano, basil, black pepper, and red pepper flakes (optional)
Simmer sauce 10 to 20 minutes, adding a splash of pasta water to loosen if needed
Add drained spaghetti to the sauce
Toss to coat, adding more reserved pasta water as needed
Serve with grated Parmesan (optional)