01 - Preheat the oven to 350°F and lightly grease a 12-cup muffin tin or line with silicone liners.
02 - In a skillet over medium heat, brown turkey sausage, breaking it into crumbles with a spatula. Drain any excess fat.
03 - Add red bell pepper and spinach to the cooked sausage and sauté for 2 to 3 minutes until softened. Set aside to cool slightly.
04 - In a large mixing bowl, whisk together eggs, milk, garlic powder, paprika, salt, and pepper until well combined.
05 - Stir the sausage and vegetable mixture, green onions, and shredded cheese (if using) into the eggs. Mix thoroughly.
06 - Distribute the egg mixture evenly among the muffin cups, filling each about three-quarters full.
07 - Bake for 20 to 25 minutes, or until fully set and lightly golden on top.
08 - Let stand for 5 minutes before removing from the pan. Serve warm or cool completely for storage.