1 egg beaten with 1 tablespoon water, for egg wash
To prepare the Almond Cream: in a food processor, combine the almonds, sugar, and flour. Process to a mealy consistency. Add the butter, a piece at a time. Add the eggs, one at a time. Continue to process until smooth. Refrigerate at least 1 hour before use.
Roll out the puff pastry to about 1/8-inch thickness. Cut one 10-inch circle and one 11-inch circle. Place the smaller circle on a parchment lined baking sheet. Brush the edge with egg wash. Spread the almond cream in the center, leaving the outer 2 inches of the circle clean. Cover with the larger circle and lightly press down the edges. Brush the top with egg wash. Refrigerate at least 30 minutes before decorating.
Preheat the oven to 375 degrees F.
Using the dull edge of a paring knife, press it against the sides of the Pithivier to seal. Decorate the top by lightly cutting from the center moving towards the edge in half circles, leaving about 1/2-inch spaces between the cuts. Put a couple of vents and place in a parchment lined baking sheet. Bake for 40 minutes or until puff pastry is baked. Serve warm.