2
Sauté mushrooms over medium heat in a frying pan until mushrooms are soft and cooked. Set aside to cool.
3
Halve the cherry tomatoes and chop the red onion and bell pepper.
4
In a large mixing bowl, whisk together eggs, milk, garlic powder, black pepper, and salt.
5
Add cherry tomatoes, bell pepper, onion, and mushrooms to egg mixture. Rip the spinach into smaller pieces as you add the spinach to the egg mixture as well. Add half of the cheddar cheese, and mix to combine ingredients.
6
Pour the bowl contents into a greased 9x13 inch baking dish. Use a spatula or spoon to even out the vegetables across the dish.
7
Bake for 20 minutes, then add the remaining half of the cheese on top of the casserole. Bake for an additional 20 minutes - the casserole is done when a knife comes out clean.