Preheat the oven to 400 degrees and line a large sheet pan with parchment paper.
Roll the puff pastry out to a 9"x 12" rectangle. No need to measure just make it larger than a sheet of computer paper.
Mix 2 tsp water into the egg yolk in a small bowl and brush the egg wash on the outer edge of the puff pastry. About an inch thick.
Spread the lemon curd on the inside of the egg wash border, all over the puff pastry.
Starting in one of the corners and working your way down, lay the apples. Then start on the row next to the middle row and work your way out from there. Make sure the apples are still within the egg wash border.
Sprinkle the apples with the granulated sugar.
Bake the tart for 40 minutes.
When it's brown and puffed and ready to come out of the oven allow it to cool on a wire rack. While it's cooling, sprinkle it with the powdered sugar (I used a small sifter to sprinkle it evenly).
Then top with the almonds if using.
Makes 9-12 servings depending on how big you slice it. Serve with whipped cream, vanilla ice cream or nothing at all.