Heat oven to 350. Meanwhile, thaw frozen spinach and begin browning ground beef over the stovetop.
Drain ground beef and return to low heat. Add spinach to the pan and stir, heating through for about one minute.
Add seasoning packet and tomato sauce.
Place bell pepper halves on a baking stone or baking pan. Divide meat mixture evenly among bell peppers. Refrigerate any leftover meat for another meal. Bake for 15 minutes or until desired texture of bell pepper has been reached. Allow to cool and serve.