- Preheat oven to 350F.
- Mix crab, mayonnaise, shallots, lemon juice, lemon zest, garlic, salt, and pepper in bowl and set aside.
- Line baking sheet with parchment paper and oil lightly. Place one sheet of puff pastry on paper. Place fillet in center of pastry and top with spinach. Top spinach with crab mixture, evenly spread to ensure even cooking.
- Use pastry brush to paint puff pastry around salmon fillet with beaten egg. Top fillet with remaining pastry sheet and trim excess dough. (Beaten egg acts as a glue to bind pastry sheets together while baking.) Using the same brush, paint top piece of puff pastry with beaten egg and crimp top and bottom pastry sheet edges together to seal salmon inside.
- Cut vents at top of puff pastry every 2–3 inches. This will allow steam to escape so sealed pastry does not explode while baking.
- Place in preheated oven for 30–35 minutes or until pastry is golden brown and crispy. Remove from oven and allow to rest 10–15 minutes before attempting to slice. Serve with roasted carrots and potatoes or a tossed green salad and herbed rice.
Note: For the extra wow factor, form pastry into a fish shape, score “scales” with a sharp knife, and make an eye, mouth, fins, and tail with the dough trimmings.
Beverage pairing: A sparkling white or rosé wine or pale ale.