Place squash cut side up in an ungreased 13-in. x 9-in. baking dish. In a bowl, combine the cracker crumbs, pecans, brown sugar, 2 tablespoons butter and nutmeg. Spoon into squash. Brush edges of squash with remaining butter. Cover and bake at 400° for 55-60 minutes or until squash is tender. Sprinkle with marshmallows. Bake, uncovered, for 3-5 minutes or until golden brown.