Melt your butter in a 2-quart sauce pan over medium-high heat. Press your garlic and add it to the melted butter, stirring a bit. Let it cook for 30 seconds, being careful not to let the garlic burn.
It's important to use freshly grated Parmesan and Romano, so the cheese will melt smoothly. (Don't use the cheese sold in a can, or the sauce will be grainy.)
This sauce makes enough for one pound of pasta. You can easily cut the sauce recipe in half for 8 ounces of pasta. Note that your sauce will take less time to come to a boil and thicken.
To reheat leftover Alfredo pasta, drizzle on a little olive oil before microwaving it, so the pasta isn't dry.