Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9 x 13" dish.
Bring a large pot of lightly salted water to a boil. Add pasta, and cook for 8 to 10 minutes or until al dente. Drain, and place in the prepared baking dish.
In a frying pan over medium heat, heat the olive oil, celery, onion and garlic in pan until tender. Add mushrooms and saute for 2-5 minutes. Set aside sauted veggies.
Melt 1/2c butter in a separate medium saucepan over medium heat. Stir in flour until well mixed. Stir in sherry/wine, milk and chicken broth. Continually stir mixture over the heat for about 5 minutes. Let it come a boil. Stir in 1 1/3 cups Parmesan cheese/ Parmy mix, and remove from heat.
Combine sauteed veggies, chicken broth mixture, turkey and peas with pasta in a bowl. Transfer to pan, on top of pasta. Top with 1/3 cup Parmy cheese.
Stir together 1/2c bread crumbs and 3T melted butter. Put over the top. Bake 1/2 hour in the preheated oven, until it's a light brown and/or bubbly and/or you can't resist any longer.