Clinton Kelly’s app for the win!

all-purpose flour (for dusting)
1 sheet puff pastry (thawed)
6 thin slices ham (minced)
1/2 cup Gruyere cheese (shredded)
1/2 cup Swiss cheese (shredded)
2 tablespoons thyme (leaves, chopped)
1 tablespoon olive oil
2 teaspoons whole grain Dijon mustard (plus more to serve)
1 egg yolk
1 teaspoon water

Preheat oven to 375ºF. Line two baking sheets with parchment paper and set aside.
On a lightly flowered surface, lightly roll out the puff pastry into a 10 x 16-inch rectangle. In a small bowl, mix together the ham, Gruyere cheese, Swiss cheese, and thyme, and set aside.
In another small bowl whisk together the olive oil and whole grain Dijon until smooth. Brush the puff pastry with Dijon mixture, and sprinkle ham mixture evenly on top.
Fold short sides of dough into center creating a letter. Fold the creased left side over right to make a log. Place log onto one of the prepared baking sheets and freeze for 15 minutes.
Meanwhile, in a small bowl combine egg yolk and water to make egg wash.
Remove from freezer and brush log with egg wash. Cut dough crosswise into 1/4-inch thick slices (about 15 pieces). Place slices back onto the baking sheets cut side up and bake until golden brown, about 10-12 minutes.
Serve with more whole grain Dijon mustard.
Tip: Substitute the ham with your favorite deli meat!