How to Make It
Light a grill. Shuck the corn, leaving on the last thin layer of green husk. Grill the ears over a hot fire, turning them frequently, until charred all over, about 10 minutes. Transfer the ears to a large bowl. Cover with plastic wrap and let steam for about 20 minutes. Unwrap the corn and cut the kernels off the cobs; you should have about 2 cups of kernels.
Preheat the oven to 350°. In a large bowl, whisk together the flour, salt, baking powder, Old Bay and a pinch of cayenne. In a small bowl, beat the egg with the buttermilk and whole milk and pour the mixture over the flour. Add the corn kernels. Using a rubber spatula, stir lightly just until the ingredients are blended.
Lightly oil a large cast-iron skillet and set it over moderately high heat. When the skillet is hot, add four 1/4-cup-size dollops of batter, spacing them evenly. Add 1/2 tablespoon of butter to the skillet and tilt to let the butter run under the cakes. Cook the corn cakes until browned on the bottom, about 3 minutes. Turn and cook until lightly browned on the second side, about 1 minute longer. Transfer the corn cakes to a rimmed baking sheet; repeat with the remaining batter and butter. Reheat the corn cakes in the oven for about 3 minutes and serve hot.