If you have a gas stove, turn on 2-3 burners and place the peppers on the burners, rotating every 2-3 minutes, or until skin is blackened. Once the skin is blackened, place in a large ziptop bag and let sit for 10 minutes. If you do not have a gas stove, preheat the broiler in your oven. Place the peppers on the rack, 3-4 inches from the broiler, and cook, rotating every 3-4 minutes, until the peppers are blackened. Follow the same process, placing in a ziptop bag and letting sit for 10 minutes.
Once the peppers have “rested” remove from the bag and use a paper towel to rub the skin off of the peppers. Cut a slit in the peppers to slightly open them, and use scissors to cut out the portion at the top of the pepper to remove the seeds. Set aside.
Preheat the oven to 375°F. Bring the vegetable broth to a boil in a small saucepan over high heat. Stir in the quinoa, and reduce the heat to low. Cover and cook the quinoa until all the liquid has been absorbed, about 12-15 minutes. Set aside.
While the quinoa cooks, heat 1 TBSP of the oil in a medium skillet over medium-high heat. Cook the onions and garlic until they are tender and lightly browned, about 3-5 minutes. Add the remaining oil and turkey and cook, stirring often, until the turkey is browned and cooked through. Stir in the salt, chili powder, cumin, and pepper. Add the spinach, and stir until it is slightly wilted. Stir in the quinoa and Greek yogurt until combined.
Divide the mixture evenly among the peppers, and top with the cheese. Place in the oven, and bae for 8-10 minutes, or until the cheese is melted and lightly browned. Remove from the oven and sprinkle evenly with cilantro.