01 - Preheat oven to 350°F and grease a 6-cup muffin tin with cooking spray or olive oil.
02 - Whisk together eggs, ranch dressing, garlic powder, salt, and black pepper in a mixing bowl until thoroughly blended.
03 - Fold in diced chicken, avocado, chopped scallions, cherry tomatoes, spinach, and shredded cheddar cheese using a spatula.
04 - Divide mixture evenly among muffin cups, filling each about three-quarters full.
05 - Bake for 22 to 25 minutes, or until egg cups are puffed and set in the center.
06 - Allow to cool for several minutes before removing from tin. Serve warm.