Melt 1/4 cup butter; add cracker crumbs and curry powder, stirring well. Press cracker mixture into bottom of a 10- x 6- x 2-inch baking dish. Set aside.
Sauté mushrooms and onion in remaining butter in a large skillet 5 minutes or until tender. Remove from heat. Stir in remaining ingredients.
Spoon mixture into prepared dish. Bake at 350° for 30 minutes.