Cook the spaghetti in a large pot of salted boiling water until al dente. Reserve 1 cup of pasta water, then drain the rest.

While the pasta is cooking, heat the olive oil in a large skillet over medium heat. Add the sliced garlic and red chili flakes, and sauté until the garlic is golden brown, about 2 minutes. Be careful not to burn the garlic.

Add the cooked spaghetti to the skillet and toss to coat in the garlic and oil mixture. If the pasta seems dry, add a bit of the reserved pasta water. Season with salt and black pepper to taste.

Remove the skillet from heat and stir in the chopped parsley.

Serve immediately, garnished with extra parsley if desired.