1) Preheat oven to 350 degrees F. Chop vegetables.
2) In a large bowl, whisk together the ingredients, except vegetables. Mix in spinach or other diced vegetables. (Note: you can opt to add some of the vegetables directly to the prepared muffin tins before or after you add the egg mixture. I usually add a few chopped tomatoes on top of the egg mixture in the muffin tins before cooking them.)
3) Use nonstick spray to grease the muffin or mini-muffin pans. Fill muffin pans 3/4 full of mixture and bake at 350 degrees F. until set in the middle and firm (about 20 minutes if egg and vegetable mixture is split into 12 muffins).