Preheat the oven to 400° F. Spray a regular-sized muffin tin with cooking spray and set it aside.
In a small bowl, mix together the melted unsalted butter (3 Tbsp) and fine sea salt (1 tsp). Then add the thawed hashbrowns (10 oz) and mix until the hashbrowns are evenly coated.
Evenly distribute the hashbrowns into each of the muffin tins. Bake the hashbrowns for 10 minutes, and then remove them from the oven. Decrease the oven temperature to 375° F.
While the hashbrowns are baking, whisk together the eggs (12), milk (¼ cup), salt (1 tsp), and black pepper (¼ tsp) in a large bowl. Set aside.
When the hashbrowns are done baking (remember to decrease the oven temperature to 375° F), evenly distribute the bacon pieces and cheese in each of the muffin tins on top of the hashbrowns. Then pour the egg mixture into each of the muffin tins, filling them almost to the brim.
Bake the egg muffins for 15-17 minutes, or until they aren't wobbly. Allow them to cool for a few minutes, then remove them from the muffin tin. Sprinkle fresh chopped parsley over the top (optional). Enjoy!