For the Gnocchi:

1. On a large flat surface or in a large bowl, combine the sweet potato puree with salt, nutmeg, and pepper. Add 1/2 cup flour at a time, mixing well with your hands after each addition, until the dough comes together to resemble a pasta dough. You may not need to use all of the flour. As soon as you have a soft, slightly elastic dough, shape it into a ball and divide it into 4 equal portions.
2. Fill a large stockpot with water and a handful of salt. Place on the stove over high heat, and bring to a boil.
3. Meanwhile, with floured hands, roll each of the four portions into logs with a 1/2-inch thickness. Dust with flour if the dough feels sticky.
4. Use a floured knife or pastry cutter to slice the logs into 1-inch squares.
5. Once the water is boiling, carefully add half of the gnocchi. Stir with a spoon for the first 30 seconds to prevent them from sticking to the bottom of the pan.
6. Cook for about five minutes, or until the gnocchi float to the top of the water. Once they float, remove them with a slotted spoon and transfer to a large plate.
7. Repeat the process with the remaining gnocchi.

For the Sauce and Assembly:

1. Once all the gnocchi have cooked, prepare the sauce. Chop the butter into evenly sized cubes. Heat the butter in a saucepan on medium heat. Once it’s completely melted, add the chopped sage leaves. Keep on the heat until the butter darkens and smells nutty, then lower the heat.
2. Place the half of the gnocchi in the pan, rolling them around for a minute or two to coat with butter. Remove them to a plate. Repeat with the second batch.
3. Top gnocchi with shredded pecorino cheese and serve warm.