Cut turkey into bite sized pieces. Melt butter in a saucepan, then stir in flour; cooking until it starts to bubble. Gradually add chicken stock, stirring until sauce thickens, then add soymilk; salt and pepper and cheese. Add turkey and mushrooms and slowly simmer. Meanwhile cook pasta according to package instructions, drain and stir into the turkey mixture. Pour into a non-stick baking dish. Bake at 450° until heated through and cheese has melted.