In a pan, heat olive oil and add onion, red pepper, mushroom and spinach, cook about 3-5 minutes. Let cool.
Spray muffin tins with cooking spray and add vegetable mixture evenly to 12 of the mini tins and 6 of the larger tins.
Add egg mixture to each muffin well, filling ¾ way full.
Cook at 350F degrees for 15-20 minutes until golden brown and set in the middle when you lightly shake the pan.
Notes
Optional add-ins or toppings- Cheese –cheddar, feta and goat cheese are only a few of my favorites. - Herbs and spices--basil is great, or chipotle powder for some spice. - Top with avocado slices or some salsa.