In a saucepan whisk milk in a stream into flour until smooth. Add dried porcin i and bring sauce to a boil over moderate heat, stirring and scraping up any fl our clinging to bottom of pan. Add salt to taste and cook over moderately low heat, stirring, about 5 minutes.
Pour sauce through a sieve into a bowl, pressing hard on mushrooms, and transfe r cooked mushrooms to a cutting board. Mince cooked mushrooms fine and return to sauce. Transfer 1/4 c sauce to a small saucepan and reserve. Into remainin g sauce whisk 3 tbsp Parmesan cheese and salt and pepper to taste and reserve.
In large kettle bring 4 qts water and salt to boil for noodles. Add noodles an d boil 40 seconds. Drain noodles in colander and transfer immediately to bowl of cold water. Drain noodles immediately and transfer to a bowl.
In non-stick skillet heat oil over moderately high heat unti hot but not smokin g and stir in fresh mushrooms. Saute mushrooms, stirring, 1 minute and cook co vered, over moderately low heat 3 minutes or until wilted and tender. Increase heat to moderately high and saute mushrooms, uncovered, stirring until all of liquid mushrooms give off is evaporated. Stir mushrooms into noodles.
Preheat oven to 375� and spray a 9" round baking dish or gratin dish with cookin g spray.
In a large bowl with an electic mixer beat egg whites with a pinch salt until t hey just hold stiff peaks. Partially fold whites into sauce in bowl and fold n oodle mixture in gently. Transfer mixture to baking dish and sprinkle with rem aining 2 tbsp of Parmesan cheese. Bake in middle of oven 25 minutes or until j ust set in center and slightly puffed.
Preheat boiler. Add just enough water to reserved sauce in pan to reach consis tency of heavy cream and heat until just heated through. Broil souffle about 4 " from heat until crisp and golden, about 30 seconds.
Serve souffle with a small amount of sauce spooned around each serving.