1. Preheat oven to 400°F (200°C), pierce sweet potatoes with a fork and roast on a baking sheet until tender, about 45–50 minutes.

2. Allow roasted sweet potatoes to cool slightly, scoop out flesh and pass through a ricer or mash until smooth; let cool completely.

3. On a lightly floured surface, make a well in the sweet potato purée, add beaten egg and salt, then gently mix.

4. Gradually incorporate flour into the mixture until a soft, slightly tacky dough forms, adding more flour only if needed.

5. Divide dough into four portions, roll each into a 1/2 inch thick log, and cut into 1 inch pieces; dust with flour to prevent sticking.

6. Bring a large pot of salted water to a boil, cook gnocchi in batches until they float, about 2–3 minutes, then cook 30 seconds longer and transfer to a plate.

7. In a large skillet over medium heat, melt butter and cook until it foams and turns golden brown, about 3–4 minutes.

8. Add sage leaves to the browned butter and cook until crisp, then add cooked gnocchi and toss to coat.

9. Season with salt and pepper, sprinkle with Parmesan if desired, and serve immediately.