Preheat oven: Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
Prepare the filling: On one half of the puff pastry sheet, spread the Dijon mustard evenly (if using). Top with the grated cheese and sliced ham.
Fold and cut: Fold the other half of the puff pastry over the filling to create a sandwich.
Using a sharp knife, cut the pastry into strips about 1 inch wide.
You can twist the strips for a fun presentation.
Brush with egg wash: Brush the tops of the pastry sticks with the beaten egg.
Bake: Bake for 12-15 minutes, or until golden brown and puffed.
Cool and serve: Let the sticks cool slightly on a wire rack before serving.
Tips and Variations: