1
Preheat oven to 350 degrees F. Prepare pasta according to package directions.
2
While pasta is cooking, melt 1 tablespoon margarine in skillet over medium-high heat. Add mushrooms and saute 2 to 3 minutes. Drain off any liquid and set mushrooms aside.
3
Place the remaining margarine in the skillet and melt over medium-low heat. With a wire whisk, stir in flour.
4
Gradually add the Dijon mustard, milk, and salt, stirring constantly until mixture boils and thickens. Once thickened, stir in mushrooms and remove from heat.
5
When pasta is done, drain well. Return pasta to the pot and add chicken, mushroom mixture, pimentos, and cheese.
6
Combine all ingredients together and transfer to a 2-quart casserole dish. Bake for 15 minutes or until heated through. Serve immediatly.