Tuna Melt Bread Boxes

Name: Tuna Melt Bread Boxes
Ingredients: 1 loaf unsliced white bread (preferably Pullman), at least 12 inches long; 6 tablespoons unsalted butter, cubed; Kosher salt; 1 1/3 cups kettle-style potato chips; 12 slices American cheese; 1/2 cup mayonnaise; 2 tablespoons Dijon mustard; 3 stalks celery, cut into small dice (about 1 heaping cup); 1 large shallot, finely chopped (about 1/3 cup); Hot sauce, as needed; Four 5-ounce cans tuna in water, well drained; 1 dill pickle, drained, cut into 16 slices and patted dry; 4 thin slices beefsteak tomato; 1 cup sprouts, optional