Mont Blanc (chestnut cream cake)

Make the Genoise

1. Setup a double boiler by filling a pot large enough to hold your mixing bowl and bring the water to a simmer. Move your oven rack to the middle position and preheat to 400 degrees F. Prep an 18" x 13" jelly roll pan by lining it with parchment paper and buttering the paper.
2. Put the eggs, yolks, sugar and salt in a metal mixing bowl and whisk to combine. Put the bowl in your double boiler and whisk, heating until the mixture reaches 100 degrees F (luke warm). Mount the bowl on the mixer and beat with the whisk attachment for 5 minutes. The volume will triple and pale yellow ribbons of egg will flow off the whisk when they're ready.
3. Combine the flour and cornstarch. When the egg mixture is ready, sift ⅓ of the flour mixture into the eggs and fold together. Repeat twice more, folding between each addition until you can't see any more clumps of flour. Pour into the prepared baking sheet and bake for 7-10 minutes or until a knife comes out clean.
4. When it's done, slide the whole thing off the baking sheet onto a wire rack to cool.

Make the chestnut puree

1. Slice the vanilla bean in half length wise and scrape the seeds into a small saucepan. Add the cream, sugar and whisk in the yolk. Heat over low heat, continually stirring until the mixture begins to thicken. Take the pan off the heat and allow the vanilla bean to steep while the mixture cools.
2. When the mixture is cool, put it in a food processor along with the pureed chestnuts. Blitz until smooth and creamy. Put a spoonful of chestnut puree in the double mesh strainer over a bowl and press through using a spatula. Strain the rest of the chestnut puree, cover and set aside.

Make Chestnut Cream

1. In the clean dry bowl of an electric mixer, add ¾ C of heavy cream. Using the whisk attachment, beat until the cream holds soft peaks. Add the sugar and beat until the sugar is incorporated. Add ⅓ C of the strained chestnut puree and mix until the cream holds firm peaks being careful not to over mix.

Assemble the Mont Blanc

1. When it's completely cooled, separate the cake from the parchment paper and trim off the edges. Cut out eight 2" x 1.5" rectangles and put them on a platter.
2. Put a large round tip on a pastry bag and fill with the chestnut cream (not the puree). Pipe 3 layers of cream onto each piece of genoise, making each layer smaller, giving it the shape of a barn roof.
3. Put a medium round tip (about the size of cooked spaghetti) on another pastry bag and fill with the chestnut puree. Starting at the bottom corner of one of the cakes and pipe chestnut puree in one continuous stream going over the top, down the other side, then looping back up and over again. Ideally you'll cover the whole thing with one continuous stream of puree, but if it breaks, just start back from where it broke and continue piping.