These muffins are totally customizable when it comes to fillings, so dream up your ultimate omelet, then whisk all of those ingredients into an egg white base. I’m a breakfast super-enthusiast, so when mornings are rushed (i.e. 8 out of 7 days a week!), I grab one or two of them from the freezer, pop them in the microwave for 1 minute and then enjoy a hot meal in one hand while holding my little guy in the other.
Preheat the oven to 350 degrees F. Grease a 12-cup muffin pan with cooking spray.
In a large bowl, whisk together the egg whites, spinach, tomatoes, mushrooms, cheese, chives, 1/2 teaspoon salt and 1/4 teaspoon pepper. Divide the mixture evenly among the 12 muffin pan cups.
Bake the muffins until the egg whites are fully cooked, for 20 to 25 minutes. Let the muffins cool for 5 minutes in the pan before using a knife to loosen them from the cups.
Top each muffin with diced avocado and serve immediately.
If freezing, transfer the fully cooled muffins to a resealable freezer bag and store them in the freezer for up to 3 months. To reheat, microwave the muffins until thawed, about 45 seconds. Then top them with the avocado and serve.