Preheat the oven to 400°F (200°C). Toss the cubed butternut squash with olive oil, salt, and pepper. Spread on a baking sheet and roast for 25-30 minutes until tender.

Once the squash is roasted, let it cool slightly, then mash it in a mixing bowl. Add the egg and salt, mixing until combined. Gradually add flour until a soft dough forms.

On a floured surface, divide the dough into sections. Roll each section into a long rope about 1/2 inch thick. Cut into 1-inch pieces and use a fork to create ridges.

Bring a large pot of salted water to a boil. Add the gnocchi and cook until they float to the surface, about 2-3 minutes. Remove with a slotted spoon and set aside.

In a skillet, melt the butter over medium heat. Add the chopped sage and cook until the butter is golden and fragrant, about 2-3 minutes. Season with salt and pepper.

Add the cooked gnocchi to the skillet with the sage butter, tossing gently to coat. Serve hot, garnished with Parmesan cheese and parsley.