Adapted only slightly from Kalyn's Kitchen, where you'll find many variations on diet-friendly egg muffins. Two muffins make a healthy high-protein breakfast serving. Makes 14 muffins.
6 oz roughly chopped mushrooms (white or cremini)
12 large eggs
2 cups grated or shredded cheese (I use Sargento reduced-fat shredded four-cheese Mexican blend from the supermarket; you can use any blend of Monterey Jack, cheddar, mozzarella, etc.)
2 Tbsp skim milk
1-1/2 tsp dried thyme leaf
1/2 tsp kosher salt
1/2 tsp fresh black pepper
Cooking spray
Preheat oven to 375°F. Prepare a standard 12-muffin tin and two small ramekins by spraying with cooking spray, or lining with paper muffin liners.
In a small, nonstick frying pan over low heat, cook the mushrooms until they have given up their liquid and are beginning to brown. (Do not add any fat to the pan.) Set aside to cool slightly while you prepare the remaining ingredients.
In a large bowl, whisk the eggs until smooth. Add the remaining ingredients, and whisk to combine. Stir in the cooled mushrooms.
Use a 1/3-cup measuring cup to fill the muffin tin and ramekins. (Or, make 12 muffins and cook the leftover as scrambled eggs.)
Bake for 35 minutes. The muffins will be puffed and brown on top. Remove from the oven and set aside to cool for 5 minutes before serving. The muffins will begin to collapse a bit as they cool.
If you're planning to freeze them, let cool completely, then pack in ziploc bags.