Preheat a grill to 400 degrees or high with indirect heat. In a large bowl, sift together 1 cup confectioners sugar, the flour, cornmeal, baking powder and baking soda. In a second bowl, stir together the creamed corn, buttermilk, butter, eggs and vanilla; stir in the flour mixture until just combined. Transfer the batter to a greased 10-inch cast-iron skillet.
Place the skillet over indirect heat, cover and grill for 10 minutes. Rotate the skillet 180 degrees , cover and grill until golden-brown around the edges and almost set in the middle, about 10 minutes more. Cover the grill, wait 10 to 15 seconds (to allow the heat inside to build), then turn off the heat. Let stand until cooked through, about 10 minutes. Set aside to cool for 20 minutes. Run a knife around the edges to loosen.
In a medium bowl, whisk together the remaining 1 cup confectioners sugar, the orange peel, orange juice and salt. Just before serving, pour the glaze over the cake.