I thought you were only doing potatoes for one, haven't you got a masher? We used to use a fork (when I was a child). Potatoes for seven, that was hard work.
Some hand blenders come with an attachment for mashing potatoes. e.g. https://tinyurl.com/mwdsdcb2
If yours has one (or something similar), then that's the obvious thing to try.
If you have a stick blender, that should solve the problem. Cook spuds, chop into smaller pieces with a knife, add a drop of milk and butter and then use the blender. You can adjust milk and butter as you go along. Definitely works. :)