Total Time: 17 min
Prep: 12 min
Cook: 5 min (2 1/2 minutes each side)
Spread 1 Tablespoon of Dijon Mustard on each piece of bread and top mustard side of bread with shredded Gruyere, Truffle Zest and top with Swiss cheese. Top with other piece of bread and Spread 1 Tablespoon butter on the outside of assembled sandwich.
Heat an Iron Skillet to medium heat and place sandwich in iron skillet and cook each side until golden brown. Cut Diagonally and Enjoy!