Begin by boiling a large pot of water. Once the water is boiling, add the macaroni noodles and cook until they reach al dente stage. Drain and set aside.
While the noodles are cooking, prepare the sauce. In a large pot or dutch oven, melt one tablespoon of the butter over medium heat the sliced mushrooms. Cook until the mushrooms are softened and reduced in volume by about half, then remove from the pot and set aside.
Add the remaining butter to the pot, flour, cream cheese, and seasonings, and stir with the melted butter until it thickens.
Stir in the milk and cream. Once the milk is warm, add the cheese 1/3 at a time, stirring until melted until all of the cheese is added, the cheese is melted, and the mixture is smooth. Do not allow the cheese sauce to boil.
Add the cooked noodles to the pot and stir to combine. Allow the pasta to heat until the cheese sauce has thickened. This should take 3-5 minutes.
Add the cooked mushrooms to the pot, stir to combine, and serve.