Well most I would have said have been listed so what I'm left with is rosti.
Grate up some peeled potatoes. With a cheese grater.
Fry up some bacon then dice it up small, into bits and pieces (or ham works too).
Then fry up some diced up onions and bell peppers.
Combine the bacon bits and grated potato into the onion and pepper mix and add some spices of salt + pepper and some paprika.
Pat down the mix so it sticks together like a hash brown.
Then just put it on a plate.
You can even add cheese or garlic or other vegetables if you want.
Potato dumplings or gnocchi. Add a couple eggs and flour to make a stiff dough to your leftover mashed potatoes. Roll into your desired thickness (thicker ropes for dumplings, thinner for gnocchi). You can freeze both very well and then boil until they float when ready to cook.
Gnocchi is good with a tomato based sauce or even in soups. Potato dumplings are great with sauerkraut and a pork roast.
2 cups chilled mashed potatoes (see Note)
2 tablespoons vegetable oil
2 tablespoons unsalted butter
1/2 cup all-purpose flour, for dredging
1 1/2 teaspoons kosher salt
1/4 teaspoon freshly ground black pepper
Divide the mashed potatoes into 8 equal portions. Use your hands to form 1/2-inch thick patties.
Heat the oil with the butter in a large nonstick skillet over medium-high heat until almost smoking. Mix the flour with the salt and pepper in a pie plate. Coat the potato patties in the flour mixture. Add the potato cakes to the pan and reduce the heat to medium-low. Cook until they have formed a golden crust, 15 to 20 minutes. (Peek underneath using a spatula before turning.) Turn and cook the other side until golden brown, about 15 minutes. Season with additional salt and pepper and serve hot.
Note: Make mashed potatoes from the "innards" of the Garlic Roasted Potato Skins by mashing them with 1/2 cup hot milk and 4 tablespoons of softened, unsalted butter. Don't forget to season them with salt and pepper! Chill the mashed potatoes overnight for the best results.