Heat large cast iron skillet over medium heat until smoking. Add corn and cook, stirring occasionally until tender and charred, approx 3min. Transfer to large bowl and cool approx 10min. Wipe skillet and set aside.

Add cheddar, mayo, provolone, shallot, scallion, chile, salt and garlic to corn. Combine.

Spread butter on bread. Place bread butter side down on parchment paper. Spread cheese mixture evenly on top (approx 1/3 cup). Place rest of bread on top.

Heat skillet over medium heat. Cook sandwiches until golden brown and toasted, approx 3-4min each side.

Serve warm.