In a medium saucepan, combine the rinsed quinoa and vegetable broth. Bring to a boil, then reduce to a simmer, cover, and cook for about 15 minutes or until the quinoa is fluffy and all the liquid has been absorbed. Remove from heat and let it sit covered for 5 minutes.
While the quinoa cooks, prepare the bell peppers. Cut the tops off each pepper and remove the seeds and membranes. If needed, trim the base slightly to make them stand upright.
In a large mixing bowl, combine the cooked quinoa, cherry tomatoes, chickpeas, feta cheese, olives, red onion, garlic, oregano, basil, red pepper flakes, olive oil, salt, and pepper. Mix well until all ingredients are thoroughly combined.
Stuff each bell pepper with the quinoa mixture, pressing down gently to pack it in. Place the stuffed peppers upright in a baking dish.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25-30 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the peppers are tender.
Once cooked, remove from the oven and let cool slightly before serving.