Trim the ends off each of the Cara Cara oranges, and then slice each as thinly as possible. Remove any of the white pith from the middle as you can.
Place the orange slices in a pot.
Pour the Champagne or sparkling white wine over the oranges, trying to cover them with the liquid. Cover the pot and refrigerate for 12 to 24 hours.
Remove the pot from the fridge and place on the stove at a medium high setting.
Add the honey and sugar, stirring occasionally as you bring the mixture to a boil.
Sterilize your canning jars – you can do that in a hot dishwasher, or by soaking them in very hot water as you are cooking the marmalade.
Stir the marmalade occasionally as it boils until it reduces by about half. A candy thermometer should reach about 220 degrees Fahrenheit.
When it is thick enough, pour the marmalade into the clean jars and top with lids.
Add a roasting rack to the bottom of a large pot (you don’t want the jars to touch the bottom). Add water and bring to a boil, adding the jars so that they sit on the rack. The water should more than cover the jars. Allow to boil for about 10 minutes.
Remove the jars from the boiling water and allow to cool for about 12 hours, undisturbed.
If the jars and lids do not have a vacuum seal, you will have to store the marmalade in the fridge, where it will keep for about a month. If the seal is good, they will store for up to a year at room temperature.