Preheat the oven to 325. Place the unshucked ears of corn on the center rack of the oven and roast for 35 minutes. Let cool until they can be handled, then cut the kernels off the cobs (about 2 cups kernels). Set aside. Discard cobs. Grease a 12-inch cast iron skillet.
Cook the bacon in a medium cast iron skillet over medium heat until crisp. Remove the bacon to a paper towel to drain, reserving drippings in skillet.
Add the onion and garlic to the bacon drippings and cook, stirring occasionally, until softened. Add the jalapeno and cook, stirring, until softened, about 1 minute. Stir in the roasted corn and heat thoroughly.
In a small saucepan over medium heat, combine the milk and cream and cook until bubbles form around the edge of the pan. Remove from the heat and let cool briefly.
In a large bowl, whisk together the eggs, melted butter, masa, and cornstarch. Drizzle in the warm milk mixture, whisking constantly. Stir in the corn mixture until well blended. Stir in the thyme, sugar, and reserved bacon. Season with salt and pepper to taste.
Pour the mixture into the prepared 12-inch skillet and bake until the center is still jiggly but set, about 25 minutes.
Reprinted with permission from The Lodge Cast Iron Cookbook by The Lodge Company, Oxmoor House copyright (c) 2012