Preheat oven to 350° F. Bring a large pot of salted water to a rolling boil and cook the pasta. Drain a few minutes before the suggested directions on the package. Run cool water over the pasta to stop the cooking process. Transfer to a large mixing bowl.
In a large (heavy bottom) stock pot, melt 1/2 a stick of butter on medium high heat and add the flour to make a roux. Cook the mixture for a few minutes to take the raw flour taste out of it. Next add the milk and stir until the mixture comes to a boil and thickens. Add the cream, nutmeg, tarragon, pepper and cheeses (cream cheese, brie, Cheddar and Gouda) continuing to stir until all the cheese has melted. Add salt or pepper, to taste. Add milk or cream (to loosen up mix) or more cheese (to thicken up mix), as needed. Top cooked pasta with cheese mixture making sure to incorporate all the ingredients well.
Transfer to a buttered baking dish; top with breadcrumbs and little bits of the remaining butter. Bake for 30 to 40 minutes until the breadcrumbs are golden and the cheese is bubbling. Can be served with any entree, or with a green salad as an entrée.