01 - Preheat the oven to 350°F. Grease a 12-cup muffin tin or line with silicone liners.
02 - In a skillet over medium heat, cook turkey sausage, breaking it up with a spatula, until browned and fully cooked. Drain any excess fat.
03 - Add red bell pepper and spinach to the skillet. Sauté for 2 to 3 minutes until vegetables are softened. Remove skillet from heat and let mixture cool briefly.
04 - In a large mixing bowl, whisk together eggs, milk, garlic powder, paprika, salt, and pepper until smooth.
05 - Fold the sausage mixture, green onions, and shredded cheese (if using) into the egg mixture. Stir until evenly combined.
06 - Divide the mixture evenly among the muffin cups, filling each about three-quarters full.
07 - Bake for 20 to 25 minutes, or until muffins are set and lightly golden on top.
08 - Allow muffins to cool in the tin for 5 minutes, then carefully remove. Serve warm, or let cool completely for storage.