4 tablespoons olive oil, divided
2 large onions, halved and thinly sliced
Coarse salt and fresh ground pepper
2 teaspoons chopped fresh rosemary leaves, divided
1 pound small pasta shells
12 ounces frozen winter squash puree, thawed
1 cup grated Parmesan cheese, divided
3 slices crusty baguette, cut into 1/4 inch cubes (1 1/2 cups)
butter for baking dish

Preheat oven to 400°F.

Butter a 9 x 13 inch baking dish. Heat 3 tablespoons of the oil in a large skillet over medium- low heat. Add the onions; season with salt and pepper.
Cover and cook until the onions are soft and release their liquid, about 15 minutes.
Uncover; increase heat to medium. Cook, stirring, until the onions are browned, 20-25 minutes. Stir in 1 teaspoon of the rosemary leaves. Meanwhile, cook the pasta in a large pot of boiling, salted water for 2 minutes less than the package instructions suggest.
Drain, reserving 1 1/2 cups of the cooking water. Return the pasta to the pot.
Stir squash and reserved pasta water into the onions; simmer for 2 minutes.
Toss the squash mixture and 1/2 cup of the Parmesan cheese with the pasta. Transfer to prepared dish.
Combine the bread cubes with the remaining Parmesan cheese, rosemary, and oil; season with salt and pepper.
Top the pasta with the bread cubes; bake until golden brown, 10-15 minutes.

Serves 6

Note: Can substitute fresh squash for frozen squash. Roast whole winter squash on a rimmed baking sheet, turning occasionally, until very tender when pierced with a knife, about 1 hour, depending on size of squash. When cooled enough to handle, halve the squash lengthwise and scrape the flesh into a food processor (discard the skin and seeds). Puree until smooth.