Pumpkin Alfredo with Ricotta Stuffed Shells

Name: Pumpkin Alfredo with Ricotta Stuffed Shells
Ingredients: 12 ounces of pasta (about 26 jumbo shells); 1 cup ricotta; 1/4 cup shredded mozzarella; 1 large egg; 3 fresh basil leaves, minced; 3 fresh sage leaves, minced; 1 garlic clove, minced; 1/4 teaspoon salt; Pinch of crushed red pepper; 2 tablespoons unsalted butter; 1 shallot, minced; 3/4 cup canned pure pumpkin puree; 2 to 3 fresh sage; 2 tablespoons yogurt or labneh or creme fraiche (basically something tart!); 1/4 cup grated parmesan cheese, plus more for garnish; Pinch of nutmeg; Salt; Freshly cracked black pepper