In a large mixing bowl, combine the ground meat, reduced-sodium black beans, fire-roasted diced tomatoes, uncooked quinoa, chili powder, cumin, garlic powder, kosher salt, and ¾ cup of cheese. Mix thoroughly for about 2–3 minutes.

Carefully slice the tops off the large bell peppers and remove the seeds and membranes. Rinse the insides with cold water. Set them upright on a plate.

Generously fill each hollowed-out bell pepper with the hearty mixture, packing it tightly without overflowing.

Pour ½ cup of water into the bottom of your slow cooker. Stand the stuffed peppers upright in the cooker and cover it with a lid.

Set your slow cooker to cook on low for 6 hours or high for 3 hours, until the peppers are tender and the filling is fully cooked.

Once cooking is complete, uncover the slow cooker and sprinkle the remaining ¼ cup of cheese on top. Let it sit for an additional 3-5 minutes.

Carefully remove each stuffed pepper from the slow cooker and serve hot with optional toppings.