Preheat oven to 375 degrees. In a small saucepan add the milk and bring to a simmer.
In a separate large saucepan heat 6 tablespoons of butter over medium heat. Add the flour, whisking constantly until the flour is mixed in. Pour the warm milk into the butter/flour mixture and whisk until smooth. Add the salt, pepper and nutmeg. Taste and add more salt if needed. Stir in 1 tablespoon of chopped sage and set aside.
Add two tablespoons of butter and the oil to a large saucepan. Add the mushrooms, remaining sage and a pinch of salt. Cook for 5-7 minutes until mushrooms begin to soften.
Spray a 9x13 inch baking dish and begin to layer the ingredients starting with a light layer of the sauce on the bottom of the dish. Add a layer of noodles, a little more sauce, then mushrooms, a little mozzarella and parmesan. Repeat layers, finishing with the cheese on top.
Bake for 35-40 minutes until cheese is melted and the top is slightly browned.
Pair With Pacific Rim's Dry Riesling.