For the cornbread: Heat the oven to 350 degrees F. Remove the labels from 12 to 14 empty 14-ounce cans (leave on the bottoms). Wash and dry the cans, then brush the insides of the cans with 2 tablespoons of the melted butter. Dust the insides with cornmeal. Arrange on baking sheets.
Spread the 1/2 cup cornmeal on another baking sheet and bake until toasted, 15 to 20 minutes, stirring occasionally to avoid uneven baking. Remove from the oven and set aside to cool.
Cut the kernels from the corn cobs. Break the cobs in half. Combine the cobs, kernels, milk, salt and vanilla seeds (save the pod for the glaze) in a saucepan and place over medium heat. Bring to a simmer; adjust the heat and simmer 15 minutes. Remove the pan from the heat, cover, and let the mixture steep until cool. Strain the kernels and reserve the flavored milk and the kernels separately. Discard the cobs.
Grind the dehydrated corn to a fine powder in a food processor or blender. Put the corn powder, flour, toasted cornmeal, sugar and baking powder in a large bowl and whisk to combine. Put the flavored milk, eggs, the remaining 6 tablespoons melted butter, and the oil in a medium bowl and whisk to combine. Whisk the wet ingredients into the dry ingredients. Add the buttermilk and mix well, then mix in the strained corn kernels.
Divide the cornbread batter between the cans, filling each three-quarters full, or pour the batter into a buttered 9x13-inch pan or into buttered Mason jars. Top with the Cracker Jack.
Bake for 15 minutes, rotate the baking sheets, and then bake until the tops are golden brown and a cake tester inserted into the cans comes out clean, about another 20 minutes. (A 9x13-inch pan of cornbread will take about 45 to 50 minutes.)
While the cornbread is baking, prepare the glaze: In a small saucepan, melt the butter over low heat. Add the syrup, soda, salt, vanilla bean paste and the reserved vanilla bean pod. Bring up to a simmer and continue to simmer until the syrup thickens slightly, 10 to 15 minutes. Remove from the heat and discard the vanilla pod. Whisk in the bourbon, and set aside. (The glaze can be made ahead and reheated when needed.)
Remove the cornbread from the oven and set the cans on wire racks to cool for 10 to 15 minutes. With a fork or a skewer, poke holes into each cornbread; this will allow the syrup to soak into the bread. With a pasty brush, liberally paint the tops of the breads with syrup (or drizzle the syrup into each can). Let cool completely. If using a 9x13-inch dish, poke holes into the top of the cornbread and glaze as with the cans.
Remove the cornbreads from the cans to store as leftovers. They will keep for 2 to 3 days in an airtight container at room temperature.