On Midsummer Night, i.e. on June 21st, harvest the still green walnuts, halve them and put them in a bottle with the spent grains or grappa. Let it stand in a sunny place for a month.
Then drain the liqueur and add the other ingredients.
A week later, remove the lavender, cinnamon stick and clove again. Finished.
You can only get stomach sugar in South Tyrol. It is probably red-colored rock candy. Alternatively, you can also use brown cube candy. Marc is still a young grape brandy, which you can replace with grappa if necessary.
Depending on your personal taste, you can also do without the lavender.