Steps
1. Preheat the oven to 350°F (175°C).
2. In a bowl, whisk together eggs, salt, and pepper.
3. Stir in bell peppers, spinach, mushrooms, and cheese.
4. Pour the mixture into a greased pie dish.
5. Bake for 20-25 minutes until the quiche is set.
6. Let it cool slightly before slicing and serving.