Heat the oven to 400°F and lightly grease the cups of a mini-muffin tin.
Whisk together the mashed potatoes, eggs, ¾ cup of the cheese, the chives, and ham. Season, if necessary, with salt and pepper. The seasoning will depend on how seasoned your mashed potatoes were to begin with. Mound a spoonful of the mixture in each muffin cup. Sprinkle the tops with the remaining 1/4 cup of grated cheese. Bake for 20 minutes, or until the potato cups are set, browned on top, and hot through.
Let cool for about 5 minutes in the pan, then use a spoon or knife to gently release them from the pan. Serve immediately with dollops of sour cream, if desired.
Notes
You can bake these and refrigerate for up to 3 days. To reheat and re-crisp: arrange the puffs on a baking sheet and bake at 400°F for about 15 minutes (depending on size).More Flavoring Ideas for Mashed Potato Puffs:Loaded Baked Potato: Cheddar cheese, cooked bacon, chopped green onions, served with sour cream and chivesCurried Potato Puffs: 1 teaspoon curry powder (or to taste), chopped red onion, chopped jalapeño pepper, served with yogurt and cucumber.Goat Cheese & Spinach: Fine chopped spinach, minced garlic, crumbled goat cheese.Italian-Inspired: Finely chopped sun-dried tomatoes, chopped basil, finely chopped shallots, served with a smear of tomato sauce.