Cook pasta: Add a large pot of salted water to the stovetop and bring it to a boil. Add the pasta cook to 1 minute less than the noted time on the box (or only about 2 minutes if using fresh pasta). Save 1/3 cup of pasta water and then drain and set aside.
Prep Breadcrumbs: In a small bowl add panko, melted butter, salt, and Parmesan cheese and set aside.
Make roux: Meanwhile, in a cast iron skillet or large saute pan, add butter and heat to medium. Add flour and whisk together the butter and flour until a thick roux forms, about 1-2 minutes.
Add milk: Slowly add a little splash of milk at a time, whisking to combine it with the roux before adding more until all of the milk is combined.If you add it too quickly then the roux with "break" and you won't have the same thick creamy sauce. Add pumpkin and seasonings: Bring the sauce to a boil, add the reserved pasta water, and then reduce it to a simmer, add the pumpkin, stir to combine, and then add the thyme, ginger, salt, and pepper and stir to combine.
Add cheese: Reduce the heat to low and add the shredded cheese. Stir to melt and combine.
Add pasta: Add drained pasta and stir to combine so that all of the pasta is well coated with the cheese sauce.
Add panko: This step is optional, but if you choose to, sprinkle on breadcrumb topping and broil in the oven for 2 minutes or until the breadcrumbs are nicely toasted and browned.