Boil the water: Bring a large pot of salted water to a boil.

Add the spaghetti: Add the spaghetti to the boiling water and cook it until just shy of done, then reserve 1 cup of the pasta water before draining.

Warm the garlic: While the pasta cooks, combine the olive oil and garlic in a large skillet over medium-low heat and cook until the garlic is pale gold and fragrant.

Bloom the chile: Stir the red-pepper flakes into the skillet and cook for 15 seconds.

Toss the spaghetti: Add the drained spaghetti to the skillet with 1/2 cup of the pasta water and toss until the liquid turns glossy and coats the noodles.

Adjust the sauce: Add more pasta water a splash at a time if the pan looks dry, then toss in the parsley.

Serve right away: Twist the spaghetti into bowls and serve with lemon wedges if you want a brighter finish.