Slow cooker: Put all ingredients in the slow cooker and stir. Cook on high for 1 hour and then on low for 6 hours or more. Remove the bay leaves before serving.
Stove: Put all ingredients in the 6-quart pot and stir. Cover and cook on medium until the sauce just begins to boil, then reduce heat to low and simmer for about 2-1/2 hours. Remove the bay leaves before serving.