In a large skillet over medium heat, cook the chicken gizzards until they are browned and tender, about 10 minutes. Remove from the skillet and set aside. In the same skillet, cook the ground beef until browned, making sure to drain off any excess fat.

To the skillet with the beef, add the celery, onions, bell peppers, and garlic. Sauté until the vegetables are softened, about 5-7 minutes.

Add the cooked gizzards back into the skillet. Stir in the Cajun seasoning, crushed red pepper flakes, and chicken broth. Let it simmer for about 5 minutes to allow the flavors to blend.

Stir in the cooked rice, green onions, and parsley. Taste and adjust seasoning with salt and pepper if needed. Let the mixture cool slightly.

Preheat your oven to 350°F. Arrange the bell peppers in a baking dish, standing upright. Spoon the dirty rice mixture into each bell pepper, packing them tightly.

Pour about 1/4 cup of chicken broth into the bottom of the baking dish to keep the peppers moist. Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for another 10-15 minutes, or until the peppers are tender.

Remove the peppers from the oven, sprinkle with a little extra chopped parsley or green onions for garnish, and serve hot!