Bring a large pot of generously salted water to a rolling boil. Add the spaghetti and cook until al dente according to package instructions.

While the pasta cooks, slice your garlic thinly and uniformly. This ensures even cooking and prevents burning.

In a large skillet, heat the olive oil over medium-low heat. Add the sliced garlic and red pepper flakes, cooking gently until the garlic turns golden brown (about 3-4 minutes). Be careful not to let it burn!

Before draining the pasta, reserve about 1/2 cup of the cooking water. Drain the spaghetti when it's al dente.

Add the cooked pasta directly to the skillet with the garlic oil. Toss well to coat every strand with the fragrant oil. If it seems dry, add a splash of the reserved pasta water.

Add the chopped parsley, salt, and black pepper. Toss everything together until well combined.

Serve immediately, topped with grated Parmigiano-Reggiano if desired.