1. Peel sweet potatoes, cut them into large cubes and boil them in lightly salted water. Drain the water and place the sweet potatoes in a bowl, allow to cool and then mash into a puree using a potato masher or hand blender.
2. Add ricotta, parmesan and salt and stir well. Gradually fold in the wheat flour and knead the ingredients into a sticky dough.
3. Dust a work surface with flour and cut the dough into six pieces. Form a long roll out of each. Cut the roll into medium-sized gnocchi and press the typical gnocchi pattern onto each piece with the back of a fork.
4. Bring salted water to a boil in a saucepan. Add the gnocchi and cook until they float to the surface. Fish the gnocchi out of the pot with a ladle and place on a plate.
5. Simmer the butter in a pan while stirring until it turns brown and gives off a nutty aroma. Add the gnocchi and roast until golden brown.
6. Pluck, wash and add the sage leaves. Stir at low heat until all gnocchi are mixed with the sage and the butter.