1. Cut the celery into 3cm pieces and put into a pan with a tight-fitting lid along with the water, butter, sage, salt and pepper.
2. Cover and cook on high heat until the water has almost evaporated and the celery is tender. This should take no more than 10 minutes, so you will have to keep an eye on it towards the end so that it doesn’t boil dry.
3. Add the lemon and keep the celery warm.
4. Meanwhile, put all the ingredients for the candied walnuts in a frying pan and stir over medium heat for three to four minutes until everything melts together, toasts and then finally glazes. Transfer to some kitchen towel to cool.
5. Cook the gnocchi as per packet instructions and drain.
6. Finally, intersperse the gnocchi and the celery on warm plates, crumble the cheese on top along with the walnuts, grapes and celery juices.