Make a pie crust of crushed crackers and 1/2 cup melted butter. Press this mixture around the bottom and sides of a 10 inch pie plate. Sauté onions until tender, but not brown in 1/2 cup butter. Add the milk, eggs, salt, and grated cheese. Pour this mixture slowly over the crust. Bake 50 to 60 minutes at 300° until the pie is golden brown.
