Combine all the ingredients in a saucepan. Place the pot over high heat and bring the contents of the pot to a boil. Reduce the heat to medium and cook until the cranberries burst, stirring regularly. If it begins to look too thick or stick to the bottom of the pot, add a splash of water.
Fit a food mill with its finest screen and set it over a bowl. When cranberries are finished cooking, pour them into the bowl of the food mill and work them through. You could also use a fine mesh sieve and a rubber scraper if you don’t have a food mill. Mill the cranberries until all that remains in the bowl of the food mill is seeds and skins.
Set a wide mouth funnel into your well-washed can molds and pour in the warm cranberry sauce, leaving a bit of space at the top.
Cover the filled cans with plastic wrap and place them the fridge to set. If you can, give them at least 12 hours of chilling for optimum molding.
When you're ready to serve, carefully slide the butter knife down along the side of the cranberry jelly and run it in a complete circle to loosen. Take care when you to this so you don’t end up slicing all the can ridges off the jelly. Once the sauce has been loosened, invert the can into your dish and give it a little wiggle.