01 - Preheat 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 apart with a spatula, until completely browned. Drain excess fat.
03 - Add diced red bell pepper and chopped spinach to the skillet. Sauté for 2 to 3 minutes until vegetables are softened. Remove from heat and allow mixture to cool slightly.
04 - In a large mixing bowl, whisk together eggs, milk, garlic powder, paprika, salt, and pepper until well combined.
05 - Fold sausage mixture, green onions, and shredded cheddar cheese (if using) into the egg mixture. Stir until ingredients are evenly incorporated.
06 - Divide the mixture equally among the prepared muffin cups, filling each cup about three-quarters full.
07 - Bake in the preheated oven for 20 to 25 minutes, until set and lightly golden on top.
08 - Allow muffins to cool in the tin for 5 minutes before removing. Serve warm or let cool completely for storage.