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Instructions
Preheat the oven to 350 degrees F (175 degrees C). Grease an 8x8-inch baking dish.
Crumble bread into crumbs; set aside. Combine ground buffalo, onion, tomatoes, bread crumbs, egg, mustard, salt, and black pepper in a large bowl until well mixed.
Form meat mixture into a loaf shape about 8x4-inches; place in the center of the prepared baking dish. Spread ketchup evenly across top and sides of meatloaf.
Bake in the preheated oven until meat is no longer pink and ketchup forms a glaze over meatloaf, about 1 1/2 hours. An instant-read thermometer inserted into center of meatloaf should read at least 165 degrees F (74 degrees C). Let stand 10 minutes before serving.