Preheat your oven to 400°F (200°C).

In a large mixing bowl, combine your cooled mashed potatoes, shredded cheese, breadcrumbs, beaten egg, salt, and pepper. Stir everything together until well incorporated.

With dampened hands, roll small portions of the mixture into balls or patties, about golf ball size.

Transfer the shaped puffs to a baking sheet lined with parchment paper, ensuring enough space between them.

Bake in the preheated oven for 25 minutes, flipping them halfway through to achieve even crispiness.

Remove from the oven, let cool slightly, and serve warm with sour cream or marinara sauce.