The first step is to bake your potatoes. There is no set number. Choose the ones that would make a good individual serving size. You want them to be cooked until very soft.
Next you want to cut a small section off the top of the potato.
Bonus: Do not toss those small sections you removed. Scoop out the potato part and save the rest for potato skins!
Next scoop out most of the potato leaving a good shell.
All of the potato goes into a large bowl with butter, salt, pepper, sour cream (or plain Greek yogurt), cheese, chives and whatever else you like. Mash everything together well.
Then put the mixture back into the potato shells. If you wish to serve them right away, bake them at 350 degrees for 25 minutes or so until they are heated through. If you want to freeze them for later, put them on a baking sheet and cover them. Once they are frozen, you can put them all in a freezer bag. To serve, thaw overnight in the refrigerator and then bake as normal.
I actually ended up with a bit too much filling so I put it into custard cups to be baked.