Wash and chop all vegetables into bite-sized pieces. Keep pieces similar for even cooking and better texture.

Preheat oven to 350°F. Grease a baking dish lightly with butter or cooking spray before filling.

Boil broccoli, cauliflower and carrots for five minutes. Drain well and let them cool slightly before mixing.

Combine sour cream, mushroom soup, mayonnaise, garlic powder, salt and pepper in a large mixing bowl thoroughly.

Stir vegetables, zucchini, onion and shredded cheese into the creamy mixture until everything coats evenly.

Spread the vegetable mixture evenly into the greased baking dish using a spoon or spatula carefully.

Mix crushed butter crackers with melted butter. Stir until crumbs become moist and slightly buttery.

Sprinkle cracker topping evenly across the casserole surface. Cover all edges for a crispy baked finish.

Place casserole into the oven. Bake for thirty-five minutes until bubbly and golden brown on top nicely.

Remove casserole carefully from oven. Let it rest five minutes before serving warm with your favorite dishes.