How to make
Put the potatoes and parsnips to boil in salted water, but not completely - they should remain slightly hard, not overcooked. Strain and leave them to cool.
Cut them into pieces and pour them into a greased fireproof dish. Mix them with the chopped sage, as much salt and black pepper as you like, pour plenty of fat and mix them with the grated Parmesan cheese and walnuts.
Pour the cooking cream over everything and bake the dish in a preheated oven at 370°F (190 degrees).
After about 15 minutes, sprinkle the dish with the mixed grated cheese and breadcrumbs and bake again until it aquires an appetizing color.
Serve the baked potatoes with parsnips slightly chilled with a green salad garnish. I like to add a few chopped garlic cloves to the dish, but it's a matter of taste.