• Preheat oven to 450°F.
• Place the bread slices on a baking sheet and toast them in the oven for about 8 to 10 minutes, or until lightly browned. You'll want to flip the slices over after about 6 to 7 minutes. Set aside.
  8 slices sourdough bread
• Lower the oven temperature to 400°F.
• Make the Béchamel sauce by melting the butter in a medium saucepan over medium heat. Whisk in the flour and stir for 1 to 2 minutes.
  3 tablespoon unsalted butter, 3 tablespoon all-purpose flour
• Slowly, add the warmed milk in increments, whisking constantly to remove any lumps. Continue whisking and stirring until thickened enough to coat the back of a wooden spoon. Remove from the heat and stir in the Dijon, nutmeg, salt, pepper, and Parmesan cheese. Let cool slightly (the sauce will thicken more as it cools).
  2 cups whole milk, 2 tablespoon Dijon mustard, ½ teaspoon ground nutmeg, ½ teaspoon Kosher salt, ½ teaspoon freshly ground black pepper, ¼ cup Parmesan cheese

Assemble the Sandwiches

• Spread a generous layer of the Béchamel on four of the toasted bread slices. Top with a generous layer of grated Gruyère, then fold the ham to fit perfectly over the cheese.
  12 oz Gruyere cheese, 12 oz deli ham
• Place the remaining four slices of bread on top of each sandwich. Spread ahick layer of Béchamel sauce over the top slice of each sandwich. Sprinkle the remaining Gruyère cheese over the Béchamel sauce.
• Place in the oven on the middle rack and bake for 8 to 10 minutes, until the cheese is melted. Turn the broiler on HIGH and broil until a few dark spots appear on the cheese (Keep an eye on them, don't let them burn!). This usually takes about 1 to 2 minutes.
• Remove from the oven and plate the sandwiches. Sprinkle the snipped chives over the top and serve at once.
  2 tablespoon chives