1. Preheat oven to 375 degrees F
2. Bring a large pot of lightly salted water to a boil. Cook pasta in the boiling water, stirring occasionally until cooked through, about 7 minutes. Drain and spray with olive oil to prevent from sticking
3. In an oven safe dish (cast iron) toast half of the chopped sage in olive oil over medium heat for 1 minute until it starts to crisp, add the breadcrumbs and toast an additional minute. Remove from the pan and set aside.
4. Melt butter in the same pan over medium heat. Stir shallots and garlic into melted butter until lightly browned, about 2 minutes.
5. Whisk milk, cornstarch, and mustard together until smooth. Stir into the saucepan until blended. Add nutritional yeast, herbs, spices and salt and pepper. Cook stirring constantly until the mixture begins to thicken over low-medium heat, about 5 minutes.
6. Add the pumpkin puree and mix until incorporated.Remove from the heat and Stir cheese into the sauce until melted. Add pasta to the sauce and stir well. Top with toasted breadcrumbs.
7. Bake in preheated oven until top is crunchy and begins to brown, about 20 minutes.