01 -
Preheat your oven to 350°F (175°C). Grease a 12-cup muffin tin generously with non-stick spray or olive oil.
02 -
In a skillet over medium heat, sauté the onions, mushrooms, and any uncooked meats (like sausage) until the onions are soft and the meat is fully cooked. Drain any excess grease.
03 -
In a large mixing bowl, whisk together the eggs, milk (if using), salt, and pepper until well combined.
04 -
Stir in the cooked vegetables, meats, cheeses, cilantro, and any other mix-ins.
05 -
Pour the egg mixture evenly into the prepared muffin cups, filling each about three-quarters full.
06 -
Bake in the preheated oven for 18-20 minutes, or until the eggs are fully set and the tops are golden.
07 -
Allow the muffins to cool in the tin for about 5 minutes before removing them. Serve warm or at room temperature.