Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve 1/2 cup of the pasta water, then drain the pasta and set aside.

In a large skillet, melt the butter over medium heat. Add the olive oil to prevent the butter from browning. Once melted, add the minced garlic and sauté for 1–2 minutes until fragrant, being careful not to burn it. If using red pepper flakes, stir them in at this stage.

Add the cooked pasta to the skillet, tossing it with the garlic butter to coat evenly. Gradually add a few tablespoons of the reserved pasta water as needed to create a smooth, silky sauce that clings to the pasta.

Sprinkle in the Parmesan cheese and chopped parsley, tossing until everything is evenly combined. Season with salt and freshly ground black pepper to taste. Adjust seasoning as needed.

Transfer the pasta to serving plates or a large serving bowl. For extra indulgence, add an additional pat of butter or a final sprinkle of Parmesan cheese. Serve immediately while warm.