Truffled Potatoes Au Gratin

1 tbl butter, softened4 tbl truffle butter1-1/2 lbs Idaho potatoes, peeled and cut into 1/4-in slices1/2 cup Gruyere cheese, grated1/2 cup Reggiano Parmigiana, grated1 cup heavy cream1 tsp sea salt1/2 tsp ground pepper1/8 tsp paprika
Preheat oven to 350°.
Butter a 1-1/2 quart baking dish with the softened butter.
Arrange a layer of potatoes in the baking dish and sprinkle some of the cheeses over them.  Continue layering potatoes and cheeses until you've used them all ending with a layer of potatoes.
In a small bowl whisk the cream with the salt & pepper and pour over the potatoes.  Dot the truffle butter over the top and sprinkle with paprika.
Bake for 1 to 1-1/4 hours, or until the potatoes are tender and golden brown on top.  Let stand for 5 minutes and then serve.