Heat the oven to 350°F and grease an eight by eight inch baking dish with butter or cooking spray.
Place the grated zucchini in a clean towel, squeeze out as much liquid as you can, and add it to a large bowl.
Add the chopped onion, corn, jalapeno, eggs, garlic powder, cumin, salt, pepper, and half of the shredded cheddar to the same bowl and stir until the vegetables are coated.
Sprinkle the corn muffin mix over the mixture and fold gently until no dry pockets remain.
Spread the batter in the prepared baking dish, smooth the top, and cover it with the rest of the cheese.
Bake for about fifty to fifty five minutes, until the center feels set and the top looks deep golden with crisp edges.
Let the casserole rest for at least ten minutes, then slice into squares and serve warm.