Preheat your oven to 350°F. While it heats, prepare your bell peppers by carefully cutting off the tops and removing all seeds and white ribs from the inside, creating hollow shells ready for filling. Stand the prepared peppers upright in a baking dish and pour about 1/2 inch of water into the bottom of the dish—this creates steam during baking to help the peppers soften evenly. The water also prevents sticking and helps cook the peppers through.
Heat a large skillet over medium-high heat and add the ground beef, breaking it apart as it cooks. Once the meat is mostly browned (about 3-4 minutes), add the salt, garlic powder, cumin, coriander, oregano, cinnamon, and cayenne pepper. Stir well to evenly coat the meat with these warm spices—this allows the flavors to bloom and infuse into the beef. Cook for another minute until fragrant, then add the chickpeas and diced tomatoes with their juice. Simmer everything together for just 1 minute to let the flavors meld slightly.
Remove the skillet from heat and stir in the cooked brown rice, fresh parsley, and 2/3 cup of the crumbled feta cheese. The residual heat will gently warm these ingredients without overcooking them. I like to fold everything together gently to distribute the feta evenly throughout—those pockets of salty cheese create wonderful bursts of flavor in every bite. Taste and adjust seasoning if needed, though the mixture should already be well-seasoned from the spices in Step 2.
Spoon the filling mixture evenly into each of the prepared pepper shells from Step 1, packing it gently but firmly so it holds together. Each pepper should be filled to just below the rim. Cover the baking dish tightly with aluminum foil and place in your preheated 350°F oven. Bake for 40 minutes—the foil traps steam that will soften the peppers while keeping the filling moist.
Remove the foil from the baking dish and sprinkle the remaining 1/3 cup of crumbled feta cheese over the top of each stuffed pepper. Return to the oven uncovered and bake for another 15 minutes until the peppers are very soft and the cheese on top is starting to soften and slightly brown in spots. The uncovered baking allows the top to dry out slightly and the cheese to develop some color, while the peppers finish becoming tender.
Remove the peppers from the oven and let them rest for 2-3 minutes. Sprinkle the fresh mint over the top of each pepper just before serving—the mint brightens the rich, warm spices and adds a cool, herbaceous finish that feels very Mediterranean. Serve warm or at room temperature depending on your preference.