Preheat your oven to 200°C (390°F). Line a baking dish with parchment for easy cleanup.
Use a sharp knife to carefully cut off the tops of the bell peppers and remove the seeds and membranes, creating a hollow cavity. Keep the tops to serve as lids if desired.
In a dry skillet over medium heat, toast the quinoa for 2-3 minutes until fragrant and slightly golden, stirring frequently. Transfer to a pot and cook with 2 cups of water until fluffy, about 15 minutes. Fluff with a fork and set aside.
While the quinoa cooks, heat 1 tablespoon of olive oil in a pan over medium heat. Sauté the minced garlic until fragrant, about 30 seconds, then add chopped tomatoes, tomato paste, cumin, smoked paprika, and cinnamon. Cook for 3-4 minutes, stirring occasionally, until the mixture is bubbling and aromatic.
Combine the cooked quinoa, tomato mixture, chopped parsley, and a drizzle of the remaining olive oil in a mixing bowl. Stir well to incorporate all flavors and spices evenly.
Stuff each hollowed-out pepper generously with the quinoa filling, pressing down lightly to pack. Place the stuffed peppers upright in the prepared baking dish.
If using, sprinkle vegan feta or cashew cheese over the top of each stuffed pepper for an extra burst of flavor.
Cover the dish loosely with foil and bake in the preheated oven for 25-30 minutes, until the peppers are tender and slightly blistered on the edges. Remove the foil in the last 5 minutes for a bit of caramelization if desired.
Carefully remove from the oven and let rest for 5 minutes. Reattach the pepper tops if you kept them, and sprinkle with extra parsley for freshness.
Serve warm directly from the dish, enjoying the fragrant spices and tender peppers with their hearty, flavorful filling.
