Prep the Muffin Pan. Preheat your oven to 375°F. Grease a 12-cup muffin tin or line with silicone muffin cups to prevent sticking.
Sauté the Veggies. In a skillet, heat a little olive oil and sauté any vegetables you’re using (onions, mushrooms, peppers, etc.) until softened. This step prevents excess moisture in your muffins.
Whisk the Eggs. In a large bowl, whisk together 10 large eggs, ½ cup milk, salt, and pepper until smooth and well combined.
Fill the Muffin Cups. Place the sautéed veggies evenly into the muffin cups. Add cheese and cooked meats (if using). Pour the egg mixture over the top, filling each cup about ¾ full.
Bake. Bake for 18–20 minutes, or until the eggs are set and slightly golden on top.
Cool & Serve. Let cool for 5 minutes before removing from the pan. Garnish with fresh herbs and enjoy warm, or cool completely for storage.