Give the marmalade a good stir to distribute the pieces of zest throughout the mixture. Use a clean ladle to transfer the marmalade to jars, leaving about 1/2 inch of headspace at the top. I find this recipe makes almost exactly 3 pints - put any extra in a small jar or bowl to cover and keep in the fridge (it isn't safe to process jars that aren't fairly full).
Put lids on jars. If canning, use a jar rack if you have one, to lower the filled jars into the boiling water in the canning kettle. Make sure there is at least an inch of water over the jars. Boil for ten minutes, lift jars out of the water and let cool. Marmalade will keep, in a cool but dry dark place for up to a year. Once opened, keep jars in the fridge.
If not canning, let jars cool to room temperature before putting them in the fridge.
