Frugal Sally 

Great use of leftover mashed potatoes.

Renee's Exchange 

Bacon Cheddar Potato Cakes - made from leftover mashed potatoes

3 slices bacon
4 cups cold leftover mashed potatoes
2 eggs
1 teaspoon onion powder
1/2 teaspoon salt
1/2 teaspoon ground black pepper
1 cup shredded Cheddar cheese

Place the bacon in a large, deep skillet,
cook over medium-high heat,
turning occasionally, until evenly browned and crisp
about 10 minutes.
Remove the bacon slices, crumble
set aside.

Leave the bacon drippings in the skillet.

Mix mashed potatoes, eggs,
onion powder, salt, and black pepper together in a bowl;
stir in the crumbled bacon and Cheddar cheese.

Form the mixture into 8 patties.
Heat the bacon drippings over medium heat,
pan-fry the patties in the drippings until crisp on each side,
about 4 minutes per side.

Possibly try mashed cauliflower instead of potato for a change!