Prepare a slow cooker by spritzing the liner with nonstick cooking spray.

In a large mixing bowl, combine the ground beef, brown rice, taco seasoning, garlic powder, black beans, ¾ cup fiesta blend cheese, and 1 cup enchilada sauce.

Scoop the mixture into each of the bell peppers, mounding at the top. Place the stuffed bell peppers into the slow cooker.

Cover the slow cooker and cook on low for 4 to 6 hours or until an instant read thermometer inserted into the center bell pepper reaches 165 degrees.

Prior to serving, pour remaining enchilada sauce over the stuffed bell peppers and top with remaining cheese. Replace the lid until the cheese has melted.

Serve topped with additional cheese and/or chopped fresh cilantro.