Start by washing and dicing your bell peppers, chopping the spinach, and dicing the onions. If you’re including turkey bacon, cook it thoroughly and chop into small pieces. Preheat your oven to 350°F (175°C) and grease your muffin tin or line it with silicone muffin cups.
In a large mixing bowl, crack all 8 eggs. Add salt, black pepper, garlic powder, and onion powder. Whisk vigorously until the mixture is smooth and slightly frothy.
Fold in the diced bell peppers, chopped spinach, diced onions, shredded cheese, and turkey bacon if using. Stir gently to combine everything evenly without breaking down the veggies too much.
Pour the egg mixture evenly into the prepared muffin tin cups, filling each about 3/4 full.
Place the muffin tin in the preheated oven and bake for 18–22 minutes. Check for doneness by inserting a toothpick in the center of a muffin; it should come out clean. The tops should be set and lightly golden.
Allow the muffins to cool in the tin for 5 minutes before transferring them to a wire rack. Once completely cooled, enjoy immediately or prepare for freezing.