1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.