Make the filling: Mix cream cheese, leek, spinach, dill, and capers in a bowl. Season with salt and pepper.
Prepare salmon: Pat the salmon dry and season both sides with salt and pepper.
Assemble: Place salmon in the center of the puff pastry. Spread the filling on top. Fold the pastry over the salmon to fully enclose it, sealing the edges well. Score the top decoratively and brush with egg wash.
Bake: Preheat oven to 400°F (200°C). Bake on a parchment-lined tray for 25–30 minutes until the pastry is golden and crisp.
Let it rest for 5 minutes before slicing.
Serve with salad or vegetables.
