· 3 tablespoons unsalted butter· 6 tablespoons all-purpose flour· 1 1/4 cups whole milk· 1 tablespoon finely chopped chipotle chile in adobo· 1 teaspoon kosher salt, plus more to taste· 1 tablespoon canola oil· 1 small yellow onion, thinly sliced· 8 slices Japanese milk bread or Pullman loaf· 16 thin slices Petit Jesu or mild soppressata (about 2 1/2 ounces)· 4 1/2 ounces Comté or Gruyère cheese, grated (about 1 1/3 cups)· 8 prunes, finely chopped· Clarified butter or ghee
Step 1Melt unsalted butter in a medium saucepan over medium. Stir in flour, and cook, stirring constantly, 1 minute. Whisk in milk until smooth. Cook over medium, stirring constantly, until thickened to a thick gravy consistency, 2 to 3 minutes. Remove from heat, and stir in chipotle and salt. Set aside. Heat oil in a medium skillet over medium-high. Add onion; cook, stirring often, until browned and tender, about 14 minutes. Remove from heat. Assemble each sandwich in this order: 1 bread slice, 2 slices Petit Jesu, 1/3 cup grated cheese, 2 tablespoons chipotle mixture, 2 chopped prunes, salt to taste, 1 tablespoon cooked onions, 2 slices Petit Jesu, and 1 bread slice. Repeat with remaining ingredients to make 3 more sandwiches. Brush outside of bread with clarified butter. Working in batches if necessary, place sandwiches in a preheated electric sandwich toaster, and cook until browned and cheese is melted, about 3 minutes.