Poke several holes in the potatoes. Microwave 3-4 minutes per side until very soft. Let cool to room temperature, then peel and mash with a large fork.
In a bowl, stir together the mashed potato, pumpkin puree, cinnamon powder, and salt.
In another larger bowl, spread 1 1/2 cups of flour. Drop the pumpkin and potato mix atop and make a well in the center. Crack the egg in the well and whisk gently. Using your hands or a large wooden spoon, fold the flour into the egg and pumpkin until well combined. If the dough seems too sticky, add 1 tablespoon of flour at a time until tacky but smooth.
Flour a clean, flat surface generously. Split the dough ball into four pieces and, working one at a time, roll into a rope about 1 inch thick. Cut pieces about 1 inch in length out of the rope. Repeat until all of the dough is used.
Bring a large pot of salted water to a gentle boil. Drop the gnocchi into the water and cook 4-5 minutes until the pieces float to the top of the water. Drain, reserving 1 cup of the starchy water, and set gnocchis onto a baking pan or a large platter.
Quarter the mushrooms. Heat 1 tablespoon olive oil in a large skillet and toss mushrooms with the oil. Cook undisturbed for 5 minutes. Add the butter, garlic, rosemary, and sage and cook until the butter browns slightly, about 3-4 minutes. Pour in the white wine and simmer until mostly reduced, about 2-3 minutes. Stream in 1/2 cup of the reserved cooking water from the gnocchi and whisk until thickened. Carefully toss the gnocchi into the sauce, adding cooking water as needed to thin. Taste for salt and pepper.