Zucchini Cornbread

Preheat oven to 400 degrees F (200 degrees C). Grease a 10-inch cast-iron skillet, and place it into the oven while it preheats. Place the zucchini, milk, onion, eggs, and vegetable oil into a blender, and pulse 5 to 8 times, until thoroughly mixed and the zucchini and onion have been chopped into very small pieces. Mix together the cornmeal, flour, sugar, baking powder, and salt in a large bowl. Pour the zucchini mixture into the cornmeal mixture, stirring to combine, and gently mix in the Cheddar cheese. Carefully pour the batter into the hot greased skillet, smooth it out with a spoon, and bake until the cornbread is golden brown and a toothpick inserted into the center comes out clean, about 30 minutes.