Preheat your oven to 350°F (175°C) and lightly grease a muffin tin.
In a large mixing bowl, whisk together the eggs, garlic powder, salt, and black pepper until frothy.
Add the chopped spinach, diced bell pepper, grated zucchini, halved cherry tomatoes, finely chopped red onion, and shredded cheese to the egg mixture and fold gently.
Pour the mixture into the prepared muffin tin, filling each cup about three-quarters full.
Bake in the preheated oven for 18-20 minutes until puffed and a toothpick comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.
Serve warm or cool for meal prep, optionally garnished with fresh herbs.
Notes
Feel free to customize with your favorite vegetables or herbs.