Melt 1/4 c of butter in a medium sauce pan, on medium heat.
Add 1/4 c flour wisk or stir(fork works best if you don't have a wisk) in well, let cook for about 1-2 minutes. I add some salt and fresh cracked black pepper at this time too. Wisk or quickly stir in 2 cups of milk, cream or half and half, or any combintation.
In the mean time, boil pasta according to directions. Has to be "just cooked". I like to use rotini or bowtie. But elbow works in a pinch.
Continue to stir and cook "cream" sauce for several minutes, until it starts to thicken.
Add in your favorite cheeses or combinations.
I use whatever I have. Usually mostly cheddar. We like cheesy so 2-3 cups of cheese.
I sometimes add in 3 or 4 American slices too.
Parmesan..just a touch couple of pinches brings out good flavor.
To make it ooh googey yummm. I like to add a couple big dollops of sour cream or about 3-4 oz or cream cheese.
Stir in cheeses and/or sour cream until melted. Take off heat and set aside.
Put cooked pasta in greased baking dish. Sometimes, I toss some cheese with the pasta..maybe a handful. Pour cheese sauce over pasta, stir through well. Pop in oven at 325-350 (depending on if you have something else in there already) and bake until it starts to just brown and bubbles a bit.