Preheat the oven to 375°F (190°C).
Place the bell peppers upright in a baking dish and set aside.
In a medium saucepan, bring the vegetable broth to a boil.
Add the rinsed quinoa to the boiling broth, reduce heat to low, cover, and simmer for 15 minutes or until the quinoa is tender and the liquid is absorbed.
While the quinoa cooks, heat olive oil in a large skillet over medium heat.
Add the chopped onion and sauté for 3-4 minutes until translucent.
Add the minced garlic and cook for an additional 1 minute until fragrant.
Add the diced zucchini and cook for 5 minutes until slightly softened.
Stir in the quartered cherry tomatoes, ground cumin, smoked paprika, black pepper, and salt. Cook for 2 minutes, stirring occasionally.
Remove the skillet from heat and stir in the cooked quinoa and half of the shredded mozzarella cheese.
Spoon the quinoa mixture evenly into each bell pepper, pressing down gently to pack the filling.
Sprinkle the remaining mozzarella cheese on top of each stuffed pepper.
Cover the baking dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 10 minutes until the cheese is melted and slightly golden.
Remove from oven and garnish with chopped fresh parsley before serving.