Steps
1. Preheat the oven to 375°F (190°C).
2. Cut the top off the bell pepper and remove any seeds and membranes.
3. In a skillet, heat olive oil over medium heat and sauté onions until translucent.
4. Add mushrooms and tomatoes, season with salt and pepper, and cook until softened.
5. Fill the bell pepper with the mushroom mixture and top with shredded cheese.
6. Place the stuffed pepper in a baking dish and bake for 25-30 minutes until the pepper is tender.
7. Serve hot and enjoy!