
Start by adding the washed, seedless green grapes to a large pot and mash all of them using a potato masher.
Turn on the heat to medium and let them cook until they start to foam.
Next, remove the excess foam using a spoon, stir everything very well and let it cook until it starts to caramelize.
Now, chop the walnuts into smaller pieces and set aside.
Then cut the large Italian bread into finger-thick slices.
Then, spread butter on one side of each slice and transfer them to a non-stick baking pan.
Place it in a preheated oven at 220° C (425° F) and toast for 5 minutes.
After the grape jam has caramelized, add the walnuts we chopped and mix to incorporate.
Transfer the jam to a jar with a lid.
Place it in the refrigerator and let it chill for at least 1 hour.
Serve the jam with the toast we prepared.