Place all ingredients in the slow cooker and give it a little stir. Add more water if necessary to cover the bones and scraps. Cook on low overnight, or 6-8 hours.
When done and slightly cool, strain out bones and scraps and place broth in a large stock pot. Simmer on stove until reduced by at least half. Let cool completely and freeze in ice cube trays.
When the cubes are frozen, pop them out and store in the freezer in a glass jar or plastic bag! Use 2 cubes of stock with 1 cup of water to get approximately 1 cup of stock, or just add cubes to any of your favorite beans, soups, pastas, and sauces.