Preheat oven to 375°F.
Mince garlic; dice mushrooms, onion, and peppers.
Using a large skillet, heat 1 tablespoon of olive oil over medium heat. Sauté mushrooms for 3-4 minutes until they begin to soften and brown. Add onion and garlic; sauté for 2 minutes more. Remove veggies from heat and set aside.
Heat remaining olive oil in same skillet and add peppers. Cook for 1-2 minutes, then add spinach and cook for 1-2 minutes more. Remove from heat and set aside.
Spray a large baking dish with cooking spray. Spread shredded potatoes out evenly in dish. Add veggies and set aside.
Whisk together eggs, milk, salt, and pepper; pour mixture over veggies; sprinkle with cheese.
Bake uncovered 40-45 minutes until the cheese has melted and becomes golden in color.
Serve with banana slices on the side.