Prepare the Gnocchi Dough: Cut cooked potatoes in half while still warm and push them through a fine sieve. To the mashed potato, add egg yolk, double zero flour, a little grating of Parmesan, and some salt. Work this into a soft dough.
Shape the Gnocchi: On a lightly floured board, roll the dough out into 2 cm logs, then cut into desired shapes. Aim for longer ones and ensure they are evenly cut.
Boil the Gnocchi: Place the gnocchi into boiling salted water. Once they rise to the top, they are ready to be removed. Place them onto an oiled tray and let them cool down.
Fry the Gnocchi: Once cool, fry the gnocchi in a pan until they get a nice golden color on both sides.
Make the Sage Butter Sauce: In the same pan, add butter, a few sage leaves, and a little bit of garlic. Roast off nicely and once the butter starts to brown, remove the pan from the heat and add a touch of lemon juice.
Serve: Pour the sage butter sauce all over the gnocchi. Finish with some cracked black pepper and grated Parmesan.