Wash the peaches, cut them crosswise and blanch them briefly in boiling water. Quench cold and peel the skin. Then cut the peaches in half, stone them and crush them into pieces with a blender.
Wash the orange with hot water and peel the peel into fine strips with a julienne knife. Put the fruit mass into a saucepan, add the orange peel, Cointreau and jam sugar and mix well. Bring to the boil over a high heat while stirring and let it boil for 3 minutes while stirring continuously.
Fill the jam hot into the prepared jars, close them, turn them over immediately and leave them on the lid for about 5 minutes.