These low-carb egg "muffins" are a simple breakfast, great for meal prepping. They store well in the in the fridge for up to a week, or you can freeze them and store for up to three months. This version call for frozen spinach, but you could use 1 cup of any fresh or frozen vegetables that you have on hand. You can eat these muffins as is, or get creative: make a sandwich with toast or a whole-wheat english muffin; cut in half and make a breakfast burrito with some other favorite fillings; or serve on top of a bed of lettuce for a low-carb, veggie-packed breakfast or lunch.