1. Preheat oven to 350°F (175°C). Thoroughly grease a 12-cup standard muffin tin with nonstick cooking spray or butter.

2. Heat a large skillet over medium heat. Add ground turkey sausage and cook, breaking it up, until browned (5-7 minutes). Drain excess grease.

3. Add diced bell pepper and chopped spinach to the skillet with sausage. Sauté for 3-5 minutes until pepper softens and spinach wilts. Remove from heat and cool slightly.

4. In a large bowl, whisk 12 eggs until frothy. Add milk, salt, and pepper; whisk to combine.

5. Fold the cooled sausage and vegetable mixture into the eggs, then stir in the shredded cheese until evenly distributed.

6. Pour the mixture into the prepared muffin cups, filling each about two-thirds full.

7. Bake for 18-22 minutes until set and lightly golden. A toothpick inserted in the center should come out clean.

8. Cool in the tin for 5 minutes, then loosen edges with a spatula and transfer to a wire rack to cool completely.