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 up with a spatula until browned and cooked through. Drain off any excess fat.
03 - Add diced red bell pepper and chopped spinach to the skillet. Sauté for 2 to 3 minutes until the vegetables are softened. Remove from heat and let cool slightly.
04 - In a large mixing bowl, whisk together eggs, milk, garlic powder, paprika, salt, and pepper until well combined.
05 - Add the sausage mixture, green onions, and shredded cheddar cheese (if using) to the egg mixture. Stir until fully incorporated.
06 - Evenly divide the mixture among the prepared muffin cups, filling each about three-quarters full.
07 - Bake for 20 to 25 minutes 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.