Preheat the oven to 375°F (190°C).
Cut the tops off the bell peppers and remove the seeds and membranes. Set aside.
Heat the garlic-infused olive oil in a large skillet over medium heat.
Add the ground beef to the skillet and cook until browned and cooked through, breaking it apart with a spoon, about 6-8 minutes.
Add the diced carrot and zucchini to the skillet and cook for 4-5 minutes until slightly softened.
Stir in the cooked quinoa, drained diced tomatoes, dried oregano, dried basil, smoked paprika, salt, and black pepper. Cook for another 2-3 minutes to combine flavors.
Remove the skillet from heat and stir in the chopped fresh parsley.
Place the bell peppers upright in a baking dish and spoon the beef and quinoa mixture evenly into each pepper.
If using, sprinkle shredded cheddar cheese on top of each stuffed pepper.
Cover the baking dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 10-15 minutes until the peppers are tender and the cheese is melted and golden.
Remove from the oven and let cool for 5 minutes before serving.