Total time 30 min
To cook the potatoes: place them in a saucepan filled with cold and salted water 3 - 4 inches above them. Allow 20 - 40 minutes (depending on the type and quantity) as the water comes to a boil.
Pierce one of the potatoes with a knife to see if they’re well cooked. If it comes out easily and isn’t stuck then they’re done.
Drain the potatoes in a colander and when they’ve cooled, peel them, add butter and mash with a potato masher (if you don’t have one, use a fork).