Heat the butter in a sauce pot, add the flour and mix together until consistent throughout. Cook for 1 to 2 minutes on medium-high to high heat.
Add half of the milk and stir vigorously, watch the sauce start to get thick, then add the remaining half of the milk or cream and stir vigorously, and watch the sauce get thick again. Cook for 15 minutes on low to medium heat, stirring occasionally.
Remove completely from the heat and add the cheese. Mix until cheese is melted and sauce looks consistent throughout. Add and adjust the seasoning with salt and pepper to taste.
Combine water and salt in a sauce pan and bring to a boil. Add noodles and cook for approximately 10-15 minutes.
Strain noodles from the hot water and lightly coat in canola or vegetable oil (Optional). Chill noodles by running under cold water before oiling to stop cooking if reserving for later use.
Combine Noodles and Sauce stir until mixture looks consistent throughout. Finish by topping sauce and noodles with two tablespoons of White Truffle Oil.