1. Make the relish: In a saucepan over high heat, combine 3 peeled, cored, and finely diced Anjou pears, 5 tablespoons apple cider vinegar, and 1 teaspoon chile flakes. Bring to a boil; reduce by simmering for 10 to 12 minutes. Remove from heat and season. Cool 2 hours.
2. For each sandwich, begin with a 1-inch thick slice of country white or sourdough. Top with a slice of fontina followed by ½ tablespoon pear relish, 2 pieces of cooked bacon, another ½ tablespoon pear relish, another slice of cheese, and another piece of bread.
3. Place sandwich over 1 tablespoon of butter over high heat in an ovenproof pan. Lower to medium; cook for 3 to 5 minutes, then flip and cook for 3 to 5 more minutes. Place pan in a 350° oven for 5 to 7 minutes. Just before serving, rub each side of the sandwich with the cut side of a halved garlic clove.
—Inset illustrations by Peter James Field