Put the potatoes in a large pot and cover them with cold water. Turn on the heat and boil for about 30–40 minutes, depending on the size. Peel and mash the potatoes, then let them cool slightly on a work surface.
While they are cooling, chop the fontina and the speck in a blender.
Add the flour, the egg and a pinch of salt to the mashed potatoes and knead well with your hands until you obtain a soft and smooth dough. Take portions of dough and roll them into little rolls about 2 cm thick. Use a knife to cut them into small pieces, ensuring they aren’t too small. Flatten each gnocchi slightly and place a little of the speck and cheese filling in the centre. Shape the dough into a ball and place it on a floured tray.
To prepare the sauce, soak the breadcrumbs in the milk for approx. 10 minutes. In a blender, finely chop the Parmesan, walnut kernels, and garlic. Then squeeze the bread crumbs, add it to the blender along with the oil, and blend everything together.
Cook the gnocchi in salt water until they rise to the surface. Drain them and sauté them in a pan together with the sauce, then serve hot.
