Heat the oven to 400ºF and set a rack in the middle. Butter a 9 x 13 baking dish or ovenproof ceramic baker.
Bring a large pot of salted water to a boil, add the corn and cook until the kernels are just tender, about 5 minutes. Drain and allow to cool for 10 minutes, then cut the kernels off using a sharp knife. (Alternatively, add the corn and 1/4 cup water to a large sealable bag, fold the top of the bag over loosely, and microwave on full power until the kernels are tender, 5 to 7 minutes. Carefully remove the bag and open it to let the steam escape; let the corn rest for 10 minutes.)
Whisk together the flour, cornmeal, sugar, baking powder and kosher salt in a large bowl. Add the eggs, garlic, oil, sour cream and butter to a medium bowl and whisk until combined. Make a well in the center of the dry ingredients and pour in the egg mixture, along with the creamed corn, fresh corn kernels, all but 1/2 cup of the Seriously Sharp Cheddar, all of the Pepper Jack or Habanero Cheddar, and the scallions. Gently stir the batter together until there are no lumps or streaks of flour, but be careful not to over-mix.
Pour the batter into the prepared baking dish and sprinkle the top with the remaining 1/2 cup of grated cheddar. Bake until the top is golden brown and the centre is still slightly jiggly, about 45 minutes to 1 hour. Remove from the oven and allow to cool for at least 15 minutes.
If you want a spicier pudding, substitute 2 oz of the grated Pepper Jack with 2 oz of Cabot Habanero Cheddar.