01 - Preheat oven to 350°F. Lightly grease a 12-cup muffin tin or line with silicone liners.
02 - Heat a skillet over medium heat. Cook the turkey sausage, breaking it up with a spatula, until browned and cooked through. Drain excess fat.
03 - Add red bell pepper and spinach to the skillet. Sauté for 2–3 minutes until vegetables soften. Remove from heat and let cool slightly.
04 - In a large mixing bowl, whisk together eggs, milk, garlic powder, paprika, salt, and pepper.
05 - Fold the cooked sausage mixture, green onions, and shredded cheese (if using) into the eggs and stir until just combined.
06 - Divide the mixture evenly among the prepared muffin cups, filling each around three-quarters full.
07 - Bake for 20 to 25 minutes, or until the muffins are set and lightly golden on top.
08 - Allow muffins to cool for 5 minutes before removing from the tin. Serve warm, or let cool completely for storage.