Set your oven to 375°F so it is fully hot before the muffins go in. Grease a muffin pan well, or line each cup with a parchment liner. I like liners because cleanup is almost zero.
Melt the butter in a small bowl, then set it aside for a few minutes. It should be warm, not hot. Hot butter can cook the eggs when you mix them, and nobody wants that.
Beat the eggs lightly in a bowl first. Pour in the cooled butter and whisk until the mixture looks smooth and glossy. This step helps the muffins bake up rich and evenly moist.
Add your stuffing to a large bowl. Pour the egg mixture over it and stir gently until everything is coated. I use a spoon and fold lightly so the stuffing doesn't turn mushy.
Spoon the mixture into the prepared muffin cups. Press down lightly so each muffin holds together. Fill them evenly so they bake at the same pace.
Slide the pan into the oven and bake for 20 to 24 minutes. You want the tops to look deep golden brown. Start checking at 20 minutes, because every oven runs a little different.
Let the muffins rest in the pan for 10 minutes. This short wait helps them firm up so they lift out neatly. Then serve them warm and enjoy the crisp edges.