Place apple slices in a medium heat-proof bowl; set aside. Stir together water, vinegar and sugar in a small saucepan. Bring to a boil; reduce heat. Simmer, uncovered, for 4 minutes, stirring frequently. Pour over apple slices. Cool to room temperature, stirring occasionally.

Meanwhile, cook bacon in a large nonstick skillet over medium heat for 8 to 10 minutes or until crisp. Drain on paper towels. Discard bacon drippings; wipe skillet clean.

Heat the same skillet over medium heat. Brush each side of bread with ½ Tbsp. oil. Cook bread slices in batches for 1 to 2 minutes or until lightly toasted on both sides, turning halfway through.

Place oven rack 6 in. from heat; preheat broiler to HIGH. Line a large rimmed baking pan with foil.

Place toasted bread slices, in a single layer, in prepared baking pan. Spread apple butter on 4 bread slices; layer with ham, bacon and Cheddar cheese. Drain apple slices; arrange on remaining 4 bread slices and top with Fontina cheese.

Broil topped bread slices for 2 to 3 minutes or until cheeses are melted and begin to bubble. To assemble sandwiches, invert Cheddar-topped bread slices and place on top of Fontina-topped bread slices. Cut each in half to serve.