How to Make It
Preheat oven to 350°. Cook squash in boiling water to cover in a large skillet 8 to 10 minutes or just until tender. Drain well on paper towels.
Melt butter in skillet over medium-high heat; add onion, bell pepper, and celery, and sauté 8 to 10 minutes or until vegetables are tender. Remove skillet from heat.
Stir in soup and next 4 ingredients. Gently stir in cornbread and squash. Spoon mixture into a lightly greased 13- x-9-inch baking dish.
Bake at 350° for 40 to 45 minutes or until golden.
Make It Ahead: Prepare recipe as directed through step 2. Cover unbaked casserole, and chill up to 24 hours. Let dressing come to room temperature (about 30 minutes), and bake as directed.