Looks can be deceiving. Traditional puff pastry is time consuming, but this re-invented "rough puff" uses a simple shortcut to get many textures in one bite -- crispy, flaky and buttery. Layers of baked pastry sandwich a creamy lemon custard in this dessert that is simultaneously light and rich.
For the rough puff: Combine the flour and salt in a large bowl. Add the butter and use a pastry cutter or your hands to cut or rub the butter into the flour until it is covered with flour and resembles chunky wet sand. There should still be chunks of butter visible in your mixture -- do not overwork.
Add the cold water slowly and start to mix until the dough comes together. It will still be quite shaggy and crumbly.
Lay out a large piece of plastic wrap and dump the dough in the center. Wrap the dough tightly, pressing down firmly to help compress and form it into a square. Allow the dough to rest in the refrigerator for at least 30 minutes and up to 1 day.
Put the dough on a lightly floured surface and roll out to approximately a 10-by-16-inch rectangle. (You should still see butter marbled in the dough.) Using a letter-folding technique, fold the top third down and bring the bottom third up, folding over the center like a letter. Turn the dough one-quarter and roll out again to three times its length. If the dough is too soft, chill in the refrigerator for 20 minutes. After rolling, repeat the letter fold a second time. Cut the dough in half to make 2 squares. Wrap each in plastic wrap and chill for at least 30 minutes and up to 1 day.
Preheat the oven to 400 degrees F. Line 2 baking sheets with parchment.
Roll out 1 piece of the chilled dough into a 1/4-inch-thick-square (or slightly thinner). Trim the edges so they are even and cut into nine 2-by-4-inch rectangles. Move the dough rectangles to one of the prepared baking sheets and chill for 20 minutes. Repeat the rolling, cutting and chilling process with the remaining piece of dough.
Dust the dough rectangles lightly with confectioners' sugar and place a second piece of parchment on top. Top with a second baking sheet to control the rise of the dough.
Bake for 20 minutes. Remove the top baking sheet and parchment paper and continue baking until deep golden brown, about 10 minutes. Transfer the pastry pieces to a wire rack to cool completely.
For the lemon cream: Bring the lemon juice to a simmer in a medium saucepan. Whisk together the lemon zest, sugar, eggs and egg yolk in a small bowl. When the lemon juice begins to simmer, temper the egg mixture by adding a small amount of hot liquid to the eggs while constantly whisking. Add the warmed egg mixture back to the pot and continue to cook over medium heat, whisking continuously. When the mixture is thick enough to coat the back of a spoon, strain the curd through a fine-mesh strainer into a medium bowl. Finish by whisking the butter into the hot curd. Cool completely in the refrigerator.
In the bowl of a stand mixer fitted with a whisk attachment, add heavy cream and powdered sugar and whip to soft peaks.
Fold the cooled lemon curd into the whipped cream, taking care not to deflate the mixture too much. Scoop the lemon cream into a piping bag fitted with a large star tip and keep refrigerated until ready to use.
For the blueberry coulis: Add the blueberries, sugar, lemon juice and 1/4 cup water to a medium saucepan. Bring the mixture to a boil, stirring to make sure the sugar dissolves. Continue to boil for 10 minutes, until the mixture thickens and coats the back of a spoon. Strain the coulis through a fine-mesh strainer and cool completely.
To build the Napoleons, drizzle the blueberry coulis onto a plate. Pipe the lemon cream onto one pastry rectangle from end to end. Top with a second piece of pastry and repeat the piping with lemon cream. Top with a third piece of pastry and pipe one more layer of lemon cream. Garnish with fresh blueberries and raspberries.
Once baked, the pastry is quite brittle. Be careful when moving and building.