Cook pasta according to package directions (I recommend cooking 1-2 minutes less than the box time so it's slightly al dente). Drain the pasta and set aside.
To make the toasted breadcrumbs: in a small pan, melt the butter over medium-low heat. Add in the breadcrumbs and stir gently until they turn golden brown in color, about 3-5 minutes. Pour into a separate bowl so that they don't burn and set aside.
Melt the butter in a large saucepan over medium heat. Once melted, add in the flour and stir to combine.
Allow to cook for 1 minute, then slowly whisk in the half and half.
Add in the pumpkin, salt, nutmeg, and cayenne and continue to cook until the sauce has thickened, about 5 minutes.
Once the sauce has thickened, add in the cheeses and fresh sage and stir until the cheese has fully melted into the sauce.
Add in the cooked pasta and stir to coat with the cheese sauce. Let cook over low heat for another 1-2 minutes.
Remove from the heat and serve immediately. Garnish with toasted breadcrumbs and fresh herbs, if desired.
Notes
Half and half yields a thick creamy sauce! For a similar consistency, use half whole milk and half heavy cream. For a thinner, lighter sauce you can just use milk. Store in an airtight container in the fridge for up to 5 days.