How to Make It
Heat a large cast-iron skillet over medium-high until smoking. Add corn kernels, and cook, stirring occasionally, until tender and charred in spots, about 3 minutes. Transfer corn to a large bowl, and let cool 10 minutes. Wipe out skillet, and set aside.
Add cheddar, mayonnaise, caciocavallo, shallot, scallions, chile, salt, and garlic to corn; stir to combine. Spread butter on one side of each bread slice. Place 6 bread slices, buttered sides down, on a piece of parchment paper, and top evenly with cheese mixture (about 1/3 cup each); spread cheese mixture in an even layer. Top with remaining bread slices, buttered sides up.
Heat cast-iron skillet over medium. Working in batches, cook sandwiches until golden brown and toasted, 3 to 4 minutes per side. Serve immediately.