Preheat oven to 375 degrees F (190 degrees C). Lightly oil a 9x13-inch baking dish.
Heat 1 tablespoon oil in skillet over medium heat. Add zucchini and onion; saute until zucchini is softened slightly, about 3 minutes. Remove from heat.
In large bowl, combine cornbread and sourdough crumbs, Swanson® Chicken Broth, sour cream, and butter. Stir in zucchini mixture, eggs, sage, poultry seasoning, salt, and pepper. Mix until evenly moistened. Spread into prepared baking dish.
Bake in preheated oven until lightly browned, 30 to 40 minutes.