poached kabocha pumpkin
Use a sharp, heavy knife to cut the kabocha in half from top top bottom. Scrape all the seeds and pith out of the center using a spoon then use a sharp vegetable peeler to remove the green skin along with any green flesh. Cut the kabocha into wedges then into 1 inch chunks. Put them in a sauce pan along with the water, sugar, vanilla bean and cinnamon stick. Cover with a lid and simmer over low heat until a fork easily passes through the kabocha (about 20-30 minutes). Do not let it boil as it will crumble and absorb too much moisture. Cool and transfer the kabocha and poaching liquid to a sealed container and refrigerate overnight, or up to a week.
Genoise (from Tartelette)
Setup a double boiler with a pot large enough to hold your mixing bowl then bring the water to a simmer. Move your oven rack to the middle position and preheat to 400 degrees F. Prep an 18u2033 x 13u2033 jelly roll pan by spraying oil on it and lining it with parchment paper (the oil helps the paper stick to the pan). Then lightly oil the top of the parchment paper.
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 a mixer and beat on high 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.
Combine the flour and cornstarch. When the egg mixture is ready, sift 1/3 of the flour mixture into the eggs and use a folding motion with a spatula to gently combine the flour with the eggs. Repeat twice more, folding between each addition until you don't see any more clumps of flour. Pour into the prepared baking sheet and smooth the top off (a clean plastic ruler works great for this). Bake for 7-8 minutes or until a knife comes out clean. Let the genoise cool on a rack.
Using either a ricer or food mill, make 1 packed cup of mashed kabocha (this step is important as it removes any fibrous bits from the kabocha). Add this to a food processor along with the sugar and process until smooth and creamy.
Whip the cream until it holds soft peaks.
Put the water in a small microwave-safe bowl and sprinkle the gelatin on top. Let it "bloom" for a few minutes or until you don't see any more powdered gelatin on top. Microwave it for 20-30 seconds until it just starts to boil (be careful, it will overflow quickly).
Mix the kabocha puree and melted gelatin together with a spatula. Dump this into the cream and continue whipping until the kabocha puree is mixed in and the cream holds stiff peaks. Be careful not to overwhip the cream.
Assemble Kabocha Cream Cake
Remove the genoise from the pan along with the parchment paper and set it on a flat surface. Cut two 8" x 8" squares out of the center of the genoise. Peel away the scraps and reserve for another use (they're great for making triffles or tiramisu).
Brush the tops of both genoise squares with 1/4 C of the poaching liquid. Peel the parchment paper away from one square and place upside down on a clean piece of parchment paper. Brush the top of this piece of genoise with half of the remaining poaching liquid.
Spread enough kabocha cream on top to make an even 3/8" layer of cream (a clean plastic ruler works great for this). Peel the second square of genoise off the parchment paper and flip upside down onto the first layer. Brush the remaining poaching liquid on top and add another 3/8" thick layer of cream.
To make the topping for the cake, use paper towels to dry off any excess liquid from the remaining poached kabocha and add them to a potato ricer. Rice the kabocha directly on top of the cake to make an even layer of orange "rice". Clean up the edges with a pastry knife and keep the cake refrigerated until ready to serve.
To serve, use a sharp knife to cut the cake into serving sized pieces then top each piece with a light sprinkle of fleur de sel and one strip of candied yuzu.