Use this recipe from "Pasta Sfoglia," by Colleen and Ron Suhanosky, to make Sweet Potato Gnocchi, Drunken Prunes, and Amaretti.
Preheat oven to 400 degrees. Wrap sweet potatoes in parchment paper-lined aluminum foil. Bake until easily pierced in the center with a fork, about 1 hour. Let cool.
Place russet potatoes in a large pot; add enough water to cover. Bring to a boil over medium-high heat and cook until easily pierced in the center with a fork. Drain, and let potatoes cool to the touch.
Wrap both sweet and white potatoes in a clean kitchen towel and rub to remove skins. Pass potatoes through a food mill fitted with a medium-hole dish, or through a ricer, into a large mixing bowl.
Spread all-purpose flour on a clean, dry work surface. Place potatoes on top of flour. Add egg, maple syrup, and salt. Using your hands, mix together ingredients on work surface until well combined to form a dough. Gently knead dough into a 10-by-8-inch rectangle. Let rest for 2 minutes.
Lightly dust a clean, dry work surface with rice flour. Cut the rectangle into 4 equal pieces. Roll each piece into a 1-inch-thick rope. Cut each rope into 1/2 inch gnocchi.
Store gnocchi on a rice flour-covered baking sheet until ready to use. Dust with rice flour. Gnocchi can also be frozen up to 2 weeks. To freeze, place them, dusted with rice flour, in a single layer on a baking sheet and freeze. Once frozen, place them one on top of the other in an airtight container. To thaw for cooking, place gnocchi in a single layer on a baking sheet in the refrigerator for not more than 1 hour before cooking. Continue cooking according to recipe directions.