Preheat your oven to 375°F (190°C) so the muffins get a head start on crispy edges.
Lightly grease a muffin tin with butter or non-stick spray to prevent sticking and help crisp the edges.
In a large bowl, mix mashed potatoes, ¾ cup of cheddar, eggs, milk, butter, parsley, salt, and pepper until well combined and thick.
Spoon the mixture into the muffin cups, filling each about ¾ full and smoothing the tops.
Sprinkle the remaining ¼ cup cheddar cheese over the tops of the muffins for a golden, melty crust.
Bake for 20–25 minutes until the tops are golden and the edges are crispy.
Let muffins cool in the tin for 5 minutes before removing them carefully with a knife.
Serve warm, garnished with extra parsley if desired.
