1. Preheat your oven to 400°F (200°C). Lightly grease a standard 12-cup muffin tin with nonstick cooking spray or melted butter, making sure to coat the sides and bottoms of each cup.

2. If using leftover mashed potatoes from the fridge, warm them slightly in the microwave until they are soft and easy to stir, but not hot. Freshly made mashed potatoes should be cooled until just warm so they do not scramble the eggs.

3. In a large mixing bowl, combine the mashed potatoes, sour cream, milk or cream, melted butter, eggs, garlic powder, onion powder, salt, and black pepper. Stir until the mixture is smooth, thick, and evenly seasoned.

4. Fold in the shredded cheddar cheese, grated Parmesan cheese, and chopped chives or green onions. If the mixture feels too stiff to scoop, add a splash more milk; if it seems loose, sprinkle in a bit more Parmesan to firm it up.

5. Divide the potato mixture evenly among the prepared muffin cups, filling each almost to the top and gently mounding and smoothing the surface with the back of a spoon.

6. Top each muffin with a small pinch of shredded mozzarella cheese and a light sprinkle of smoked paprika, if using, to encourage extra color and a cheesy crust on top.

7. Bake for 20 to 25 minutes, or until the muffins are puffed, golden on top, and the edges are crisp and lightly browned. A toothpick inserted into the center should come out mostly clean.

8. Remove the pan from the oven and let the muffins cool in the tin for 5 to 10 minutes to set. Carefully run a thin knife around the edges of each muffin and lift them out of the pan.

9. Sprinkle the warm muffins with chopped fresh parsley or extra chives and serve immediately as a side dish, snack, or part of a brunch spread.

10. To store, let leftovers cool completely, then refrigerate in an airtight container for up to 4 days or freeze for up to 2 months. Reheat in a 350°F (175°C) oven or air fryer until hot and crisp again.