Cook the pasta according to the package directions.
Wash and peel the yams, then cut into ½-inch pieces and steam for 10 minutes or until tender. Set aside a handful of pieces. Blend the rest of the yam with the remaining cheese sauce ingredients until the mixture is smooth and thick enough to hold its shape, adding water as needed.
Mix the cheesy sauce into your pasta along with the few pieces of yam you set aside, sprinkle on some cracked black pepper and enjoy!