Take off 3 zests of lemon and 3 zests of orange, slice them thinly and blanch with plenty of water.

Press the citrus fruits to retrieve the juice and the pulp.

Peal the watermelon, cut into big cubes of 3 cm and bake at very low heat during 20 minutes approximately.

Drip-dry and put back the fruit in the pan, add the juice and the zests and carry on with the baking at medium heat for 5 minutes.

Weigh to add 750 g of sugar by kilo of this first preparation. Put back to bake at medium heat so that the water evaporates slowly and the jam thickens. The pieces of watermelon then become translucent. Count approximately 1 hour to achieve this.

To finish, add the walnuts coarsely grinded, put into jars and close immediately.

Turn the pots upside down and leave to cool.

This jam is perfect for breakfast.

It can also go perfectly with a Basque sheep cheese or a fresh goat cheese.