Add the spinach, salt and pepper. Cooked until the spinach has wilted.
Add the breadcrumbs, cream cheese, parmesan and dill. Stir until mixture is evenly combined. Remove from heat and set aside.
smooth out the sheet of puff pastry. Place the salmon in the middle of the pastry and season both sides with salt and pepper.
Place several spoonfuls of the spinach mixture on top of the salmon, smoothing it out so that it does not spill over the sides.
Fold the edges of the puff pastry over the salmon and spinach, starting with the longer sides and then the shorter ends.Flip the puff pastry-wrapped salmon over and transfer to a baking sheet lined with parchment paper.
Brush the beaten egg on the top and sides of the pastry.
Score the top of the pastry with a knife, cutting shallow diagonal lines to create a crosshath pattern.