In a medium bowl, combine flour, baking powder, salt, and baking soda. Set aside.
Whisk brown sugar and white sugar into the milk and cornmeal mixture that has been soaking. Whisk in eggs. Stir in 3 tablespoons of melted butter, plus vegetable oil, vanilla, and remaining maple syrup. Reserve the last tablespoon of butter for buttering the pie dish/skillet.
Add dry ingredients to wet ingredients. Stir in 1/2 of the maple-glazed corn.
Carefully remove the hot skillet from the oven. Reduce oven temperature to 375°F [190°C]. Using a pastry brush or paper towel, brush the baking surfaces of the hot skillet with the reserved 1 tablespoon of melted butter.
Pour the batter into the hot skillet. Sprinkle the remaining maple-glazed corn evenly over the top, and place on the center rack of the oven.
Bake until the center is firm and a cake tester or toothpick inserted into the center comes out clean, about 30-35 minutes for 10-inch skillet or cast iron pie dish. Allow to cool for 10 minutes before serving.