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