Grate the zucchini and transfer it to a colander. Evenly sprinkle with salt and allow it to sit and drain for 30 minutes. Afterward, press the zucchini to expel excess moisture.

Preheat the oven to 350°F and coat a 7x10-inch baking dish with non-stick spray.

Lay the zucchini on paper towels and squeeze again to remove remaining water.

In a large bowl, combine the cornbread mix, zucchini, diced onion, eggs, Montreal Steak Seasoning, and 1½ cups of the shredded cheddar cheese. Stir thoroughly to incorporate.

Transfer the mixture into the prepared dish and smooth the top. Sprinkle the remaining cheese evenly over the surface.

Bake, uncovered, for 30 to 40 minutes, or until a toothpick inserted in the center emerges clean.

Let rest for 10 minutes before slicing and serving.