Bring a large pot of salted water to a boil. Cook spaghetti until al dente (8–10 minutes), then drain.
In a skillet over medium-low heat, melt the butter slowly.
Add garlic and cook gently to avoid burning.
Stir in parsley, salt, black pepper, and cayenne if using.
Add the cooked pasta to the skillet and toss well to coat.
Increase heat slightly and cook until the pasta absorbs some of the buttery sauce.
Adjust seasoning as needed.
Serve hot with grated Parmesan cheese on top.
This rich pasta for the poor kitchen is best enjoyed immediately while warm and creamy.