Preheat oven to 350 degrees F. Spray a 9x13-inch baking dish with nonstick cooking spray; set aside.

Melt butter in a large skillet over medium-high heat. Add zucchini and onion and sauté for 10 minutes, or until tender. Add garlic and cook for an additional minute.

In a large mixing bowl, combine cooked zucchini and onion, corn, yogurt, sour cream, eggs, salt, pepper and cheddar cheese.

Spread mixture in an even layer in prepared pan and top with bread crumbs. Spray crumbs generously with cooking spray. Bake, uncovered, for 45-50 minutes or until lightly golden brown on top.