Combine all of the ingredients into a heavy bottomed pot. Bring to a simmer over medium heat, leaving the pot uncovered. Simmer for at least 60 minutes, lowering the heat as the liquid reduces.
Check the pot frequently, particularly in the final 15 minutes of cooking to ensure it doesn't burn on the bottom. Stir occasionally, as needed.
Check for doneness. The molasses should coat the back of a spoon, and appear viscious. Tiny bubbles will be softly bubbling in the center of the pot, tightly spaced together. Use the photo in the body of the post as a reference.
Cool for 20 minutes, strain out any spices you choose to use, and pour the molasses into a glass jar. Refrigerate for up to 6 months.