1. Preheat oven to 350°. Cut squash into 1/2-inch rounds. Cook squash and next 3 ingredients in a large skillet over medium heat, stirring often, 25 minutes or until tender. Drain well, reserving broth for another use; pat squash mixture dry with paper towels.
2. Stir together mushroom soup and next 3 ingredients in a large bowl; stir in squash mixture until blended. Spoon mixture into a lightly greased 11- x 7-inch baking dish; sprinkle with crushed cornflakes.
3. Bake at 350° for 25 to 30 minutes or until golden and bubbly.