Preheat your oven to 375°F (190°C). Roast the butternut squash on a baking sheet until tender, about 25 minutes. I remember overcooking it the first time around, thinking it needed more time. It's essential to trust the process and the specified timings.

Once the squash is cool enough to handle, mash it in a bowl with ricotta, Parmesan, chopped sage, salt, and pepper. The first time I made this, I used a food processor, but found that hand-mashing gave a better texture.

Place a teaspoon of the squash mixture in the center of a wonton wrapper. Brush the edges with egg wash, place another wrapper on top, and press to seal, ensuring there are no air bubbles. Repeat with the remaining wrappers and filling.

Bring a large pot of salted water to a boil. Cook the ravioli in batches for about 2 minutes each, or until they float to the surface. Use a slotted spoon to transfer them to a greased baking dish.

To make the sauce, melt butter in a saucepan over medium heat. Stir in flour and cook for a minute. Gradually whisk in milk, roasted garlic, nutmeg, salt, and pepper. Cook, stirring constantly, until the sauce thickens. It took me a few tries to perfect the consistency. A common mistake is not simmering it long enough, so patience is key here.

Pour the sauce over the cooked ravioli. In a small bowl, mix breadcrumbs with olive oil, then sprinkle the breadcrumb mixture and mozzarella over the top.

Bake for 20-25 minutes, or until the top is golden and bubbly. Let it rest for 5 minutes before serving. Garnish with fresh sage leaves.