Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package instructions until al dente, about 8-10 minutes. Reserve about 1 cup of pasta water and then drain the pasta in a colander.
While the pasta cooks, heat the olive oil in a large skillet over medium heat.
Add the sliced garlic to the skillet and sauté gently, stirring frequently for about 2-3 minutes, or until the garlic is golden brown and fragrant.
If using, add the red pepper flakes to the garlic oil and stir for an additional 30 seconds.
Add the drained pasta directly to the skillet with the garlic oil. Toss well to combine, adding reserved pasta water as needed for a silky sauce.
Season with salt and freshly ground black pepper to taste.
Serve immediately, garnished with chopped fresh parsley and grated Parmesan cheese, if desired.
For added flavor, consider including a squeeze of lemon juice or a sprinkle of lemon zest before serving.
Feel free to customize this recipe by adding veggies such as spinach or cherry tomatoes, or protein such as grilled chicken or shrimp for a more filling meal.