Preheat your air fryer to 400°F. Place butternut squash halves cut-side down in the air fryer basket and cook for 35-40 minutes until tender when pierced with a fork.

Remove squash from air fryer and let cool for 10 minutes. Scoop out the flesh and pass through a potato ricer or mash until completely smooth. You should have about 2 cups of puree.

In a large mixing bowl, combine the butternut squash puree, beaten egg, salt, and nutmeg. Gradually add 1 3/4 cups of flour, mixing until a soft dough forms. Add remaining flour if dough is too sticky.

Turn dough onto a floured surface and knead gently 3-4 times until smooth. Divide into 8 portions and roll each into a rope about 3/4-inch thick.

Cut each rope into 3/4-inch pieces. Roll each piece over a gnocchi board or fork tines to create ridges. Place on a floured baking sheet.

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

In a large skillet, melt butter over medium heat. Add sage leaves and cook until butter turns golden brown and sage becomes crispy, about 4-5 minutes.

Add cooked gnocchi to the skillet and gently toss to coat with brown butter. Season with black pepper and serve immediately topped with grated Parmesan cheese.