Roasted Squash Shells and Cheese

Name: Roasted Squash Shells and Cheese
Ingredients: 1 medium (1 to 1 1/2 pounds) butternut squash, peeled and cut into a 1-inch dice (about 4 cups); 1 small (6 to 7 ounces) yellow onion, 1-inch dice (about 1 cup); 2 tablespoons olive oil; 1 1/4 teaspoon kosher salt, plus more for pasta water; Freshly ground black pepper; 3/4 teaspoon ground paprika; 1/2 teaspoon dried mustard; 1/8 teaspoon freshly grated nutmeg; 1-pound box of medium shells pasta; 1 1/2 cups (360 grams) low-sodium vegetable broth; 2 cups (220 grams) shredded sharp yellow Cheddar; Sriracha, for topping