To make it on the stovetop, put the cooked and drained meat and onions in a large, heavy-bottom pot instead of a crock pot. Add the remaining sauce ingredients, cover, and simmer over low heat, stirring occasionally, for one hour. Cook the spaghetti in a separate pot and add it along with 1/2 cup of pasta water to the sauce. Stir and cook over low heat for about two minutes before serving.