Step 1: Melt the butter in a medium-heavy saucepan, and add in the flour, stirring consistently until light golden brown. Using a whisk, slowly pour in the milk and cream, continuing to stir until the mixture thickens, approximately 15–20 minutes, being careful to touch all corners and bottom of the pan to avoid scorching.

Step 2: Add in the cheeses and truffle oil, and stir, adjusting seasoning as needed with white pepper and salt. Strain through a strainer to remove any scorched flour bits.

Step 3: Meanwhile, cook the pasta in salted boiling water until tender and strain through a colander. Place the pasta back in the pot and toss with cheese sauce. Serve warm.

Note:

If you are making this for a group or for a large buffet such as Thanksgiving, then you may want to make it ahead of time and place it in a Staub/baking dish. Bake with foil at 300–375°F until warmed through. Remove the foil, top with breadcrumbs and additional grated cheese, and cook until slightly golden brown on top. Serve.