• Step 1: Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or a silicone baking mat.
• Step 2: In a medium bowl, mix together the cream cheese, dill, lemon juice, Dijon mustard, salt, and pepper until well combined.
• Step 3: Place the salmon fillet in the center of the puff pastry sheet. Spread the cream cheese mixture evenly over the top of the salmon.
• Step 4: Fold the puff pastry over the salmon, sealing the edges with a fork to create a tight seal. Brush the top of the pastry with the egg wash.
• Step 5: Bake the salmon en croute for 25-30 minutes, or until the pastry is golden brown and the salmon is cooked through.
• Step 6: Remove the salmon en croute from the oven and let it rest for 5-10 minutes before slicing and serving.