Peel and cube butternut, and steam 30min until tender. Mash until smooth. Add flour, yeast, herbs, and salt. Lightly knead dough and add flour if too sticky. Divide into 4 equal portions. Using your hands, roll the first portion onto floured surface into a 3/4" thick rope. Cut 1" cylinders and roll over fork to create lines. Repeat with remaining portions. Place on parchment paper. Boil salt and water in large pot. Boil in small batches until gnocchi floats. Remove with slotted spoon and let rest 5min.