Start by bringing a pot of salted water to a boil for the pasta. Cook the pasta according to package directions.
Melt the butter in a large pot or pan. Add the minced garlic and cook for 1 minute or until fragrant. Add in the pumpkin puree and cook for 2-3 minutes.
Pour in the cream, milk, and cheeses. Stir and bring to a low simmer.
Strain the cooked pasta, reserving some of the pasta water.
Add in the pasta water to the sauce. Simmer for an additional minute. At this point the sauce should coat the back of a spoon. If it doesn't yet, try adding in another splash or heavy cream or tablespoon of pumpkin puree.
Add in the cooked pasta and mix well.
Serve with freshly cracked black pepper, if desired.