Ultimate Grilled Cheese

INGREDIENTS

• 1 cup good mayonnaise
• Kosher salt and freshly ground black pepper
• 1/4 cup freshly grated parmesan cheese
• 6 ounces aged gruyere or comte cheese
• 6 tablespoons salted butter, at room temperature
• 1/4 cup dijon mustard
• 1 white pullman loaf or sourdough bread, sliced 1/2 inch thick (12 slices)
• 12 slices thick-cut bacon, such as Nodine's applewood smoked
• 6 ounces extra-sharp cheddar, such as Cabot or Shelburne Farms