Steps
1. Preheat the oven to 375°F (190°C).
2. Cut the top off the bell pepper and remove seeds and membranes.
3. In a bowl, mix the cooked quinoa, chopped spinach, black beans, olive oil, garlic powder, cumin, salt, and pepper until well combined.
4. Stuff the bell pepper with the quinoa mixture, pressing down gently to pack it in.
5. Place the stuffed pepper in a baking dish and cover with foil.
6. Bake in the preheated oven for 25-30 minutes.
7. If using, sprinkle feta cheese on top during the last 5 minutes of baking.
8. Remove from the oven, let it cool for a minute, and enjoy!