Preheat oven to 450 degrees Fahrenheit. Add 1 Tbsp oil to your skillet. Place in oven while it is preheating.
Prepare cornbread in a mixing bowl as instructed on mix packages. Use buttermilk as a substitute for the water or milk designated on the mix. Use the same measurement for the buttermilk as designated on the mix for the other liquids.
Stir in the squash, celery, bell pepper and onion. There should be just enough batter to hold the vegetables together.
Pour batter and vegetables into heated skillet. Bake for the time designated on the mix package. You may have to bake a few minutes longer to compensate for the moisture the squash releases into the cornbread as it bakes.
Remove cornbread from oven after baking. Allow to cool, but not completely. Turn oven temperature down to 350 degrees.
While cornbread is still warm, remove from skillet and break into pieces in large mixing bowl. Add butter and mix together, breaking down the cornbread.
Add soup, broth, eggs and seasonings to cornbread mixture. Mix ingredients together until all are well-incorporated. Cornbread look almost like a batter again.
Spoon cornbread dressing into 9x13 casserole dish. Bake at 350 degrees Fahrenheit for 30- 40 minutes or until dressing is golden brown and set in the middle.
This is a moist dressing that doesn't need a gravy!This dressing can also be made ahead of time and frozen. Allow to thaw for 24 hrs and allow dish to come to room temperature before baking. If made a day before, store in fridge, then bring to room temperature before baking.