Butternut Squash-Stuffed Shells
10 ounces diced butternut squash (about 2 1/2 cups)
1 small shallot, halved  
1 clove garlic, unpeeled  
2 teaspoons olive oil  
1/4 teaspoon fresh thyme leaves, finely chopped  
1 large leaf fresh sage, finely chopped, plus more for serving  
Kosher salt and freshly ground black pepper  
30 jumbo pasta shells (about 10 ounces)  
1/4 cup vegetable broth or water  
Two 10-ounce packages frozen chopped spinach, thawed, drained and squeezed dry    
1 pound cream cheese, at room temperature  
2 cups whole-milk ricotta    
2 teaspoons red pepper flakes  
2 cups grated Parmesan, plus more for serving  
2 cups heavy cream    
2 tablespoons unsalted butter  
Pinch freshly grated nutmeg  
1 cup freshly grated mozzarella    
Instructions:
Preheat the oven to 425 degrees F.
Add the squash, shallot and garlic to a baking sheet. Drizzle with the olive oil and toss to combine. Sprinkle with the thyme, sage, 1/4 teaspoon salt and a few grinds of black pepper and toss again. Roast until the squash is tender and light golden, about 30 minutes. Let cool.    
Meanwhile, bring a large pot of water to a boil; add salt. Add the pasta shells and cook until al dente according to the package directions. Drain and let cool.  
Squeeze the roasted garlic into a small food processor or blender, add the squash, shallot and vegetable broth and puree until smooth.  
Mix together the spinach, cream cheese, ricotta, red pepper flakes, 2/3 cup of the Parmesan and 1 tablespoon salt in a large bowl. Stuff about 2 tablespoons of the spinach mixture into each shell; set aside.  
Add the pureed squash mixture, heavy cream and butter to a large skillet over medium heat. Cook, whisking frequently, until thickened, about 5 minutes. Remove from the heat and whisk in the nutmeg, 1 1/2 teaspoons salt and the remaining 1 1/3 cups Parmesan.  
Spread the cheese sauce into the bottom of a 9-by-13-inch baking dish. Arrange the stuffed shells in the baking dish seam-side up, shingling them so they all fit (you should have 5 shells along the short side and 6 shells along the long side). Top with the mozzarella. Bake until the cheese is melted and bubbling, 15 to 20 minutes. Top with more Parmesan and sage before serving.
