Wash the gooseberries, remove stems and crowns and heat in a layer of water until soft. Add orange zest and juice and return to a boil. Add all of the sugar. Stir using a wooden spoon (a metal spoon will get too hot!) until the sugar is dissolved. Test whether the jam is setting properly: put a drop of jam on a saucer and place in the refrigerator for 1 minute. If it has thickened nicely the jam is ready. Quickly fill the jars and apply the lids. Tighten the lids securely and turn the jars upside down in order for the vacuum to be created. The jam will have a shelf life of one year.
After opening, store in a cool place.