Potatoes (enough to fill a casserole dish)
1 stick butter
Salt and pepper to taste
Water
Onions (optional)

Peel and slice a casserole dish full of potatoes. Put a stick of butter or more as needed on top. Season with salt and pepper to taste. Fill casserole dish 2/3 full with water.

Cover. Put in microwave for 1 hour or until all liquid (water and butter) is almost absorbed in potatoes. Stir every 15 minutes.