Dianna, I don't actually measure, but this is about as close as I can get to the actual recipe:
enough potatoes to fill the pan you are using by 2/3. generally, for scott and i, i use 4-5 medium potatoes so that we have leftovers. i peel and slice (unless they are red skin/thin skin, then i just scrub and slice). then in a sauce pan, put a stick of butter, salt to taste, and add about 1/4-1/3 c flour. stir like you are making flour gravy. then add about 2 cups of milk. i usually start with about a cup and a half, and go up if i need to. i stir the milk into the butter/flour slowly so that it won't lump up. just like making gravy. when it is mixed well, and nice and runny, i pour it over the potatoes. if there isn't enough to cover the potatoes, i just pour more milk over the top.
then - either bake at 350 for about an hour (check after 40 minutes and every 10 minutes there after, OR put in the microwave. my microwave lets me put up to 3 temp settings in at once. so i do a few minutes (3 or 4) on high, the 7 or 8 on medium, and 6 minutes on medium high. sometimes i mix it up, but that's about the base. if the potatoes are not done when the time is up, i do it again.
the edges of the pan will brown and crisp, whether you do it in the microwave or the oven. enjoy!