Preheat your oven to 400°F (200°C). Toss the butternut squash cubes with olive oil, salt, pepper, and nutmeg. Spread them on a baking sheet in a single layer.

Roast in the preheated oven for about 25-30 minutes or until the squash is tender and starts to caramelize. Let it cool slightly, then puree in a food processor until smooth.

In a bowl, mix together the ricotta cheese, beaten egg, minced garlic, salt, and pepper until well combined.

Reduce the oven temperature to 375°F (190°C).

Spread a thin layer of butternut squash puree on the bottom of a 9x13 inch baking dish.

Layer lasagna noodles over the squash puree, followed by half of the ricotta mixture, a layer of mozzarella cheese, and a sprinkle of parmesan cheese.

Repeat with another layer of noodles, butternut squash puree, the remaining ricotta mixture, more mozzarella, and parmesan cheese.

Finish with a final layer of noodles, the rest of the butternut squash puree, and the remaining mozzarella and parmesan cheeses.

Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes.

Remove the foil and bake for an additional 25 minutes, or until the top is golden and bubbly.

Let the lasagna rest for about 10 minutes before slicing. This helps the layers set and makes serving easier.

Garnish with fresh sage leaves if desired and serve warm.