Preheat oven to 400 degrees F. Spray a 7x11 (or 9x9) inch baking dish with cooking spray.
Add the oil to a large non-stick skillet and place over medium-high heat for two minutes. Add the mushrooms, bell pepper, and onion. Cook 5 minutes, stirring occasionally.
Reduce the heat to medium-low. Add the spinach, tomatoes, garlic, rosemary, and thyme. Cook 3 minutes, stirring often.
Pour the vegetables into the baking dish. Spread them into an even layer. Let the vegetables cool for 5 minutes.
Top the vegetables with shredded cheese.
In a large bowl, add the eggs, milk, salt, and pepper. Whisk until well combined. Slowly pour the eggs evenly over the vegetables.
Bake for 30 minutes.
Cool for 5 minutes before slicing.