Preheat oven to 325 F. Spray a muffin pan cavities liberally with nonstick cooking spray or place silicone liners in the cavities.
In a large measuring cup with a spout, mixing together the eggs with the shredded spinach, bell pepper garlic powder, thyme, salt and pepper.
Pour the mixture into each muffin cavity filling 3/4 of the way full - dividing it evenly among 10 cavities.
Place in the oven and bake for 25 minutes or until firm.
Remove from the oven and let the egg muffins sit in the pan for 2-3 minutes then use a small plastic spatula to carefully remove each one from the muffin cavities. Transfer to a wire rack to cool completely then store in the refrigerator up to 5 days.