Buckwheat, Bergamot & Blood Orange Chiffon Cake

Ingredients

• 1.8 t double-acting baking powder 
• 220 g bittersweet chocolate 70% chopped ()
• 206 g buckwheat flour 
• 289 g egg whites 
• 65 g egg yolk 
• 86 g egg yolk at room temperature
• 1.5 t gelatin powder 
• 6 g tea cold (or 4 tea bags)
• 0.3 t cream of tartar 
• 1 T juice of lemon 
• 1 t sea salt fine
• 42 g sugar 
• 37 g water 
• 220 g milk whole
• 170  orange marmalade 
• 114  blood orange juice 
• 56  grapeseed oil 
• 71  kumquats 
• 114  milk whole
• 100  sugar 
• 124  caster sugar 
• 114  water 

Equipment

• bowl
• frying pan
• sauce pan
• baking paper
• oven
• knife
• whisk
• wire rack
• sieve
• cake form
• wooden spoon
• kitchen thermometer
• stand mixer
• spatula
• springform pan
• offset spatula
• immersion blender
• serrated knife
• pastry brush

Directions

1. Pour the lemon juice into a medium nonreactive bowl and add the gelatin. Stir to dissolve the gelatin, then add the marmalade and the candied citrus. Refrigerate until cool and set, about 2 hours (this can be made and refrigerated up to a day ahead).
2. To make the cake: Preheat the oven to 325F/165C. Line the bottom of 10-in/25-cm springform cake pan with parchment paper and set aside.
3. Sift together the flour, baking powder, and salt into a large bowl.
4. Add 100 g /1/2 cup of the sugar and whisk to combine.
5. In a medium bowl, whisk together the milk, egg yolks, oil, and water. Make a well in the flour, add the yolk mixture, then whisk thoroughly and quickly for about 1 minute until very smooth.
6. Put the egg whites in the bowl of a stand mixer fitted with the whisk attachment. Beat on medium speed until frothy.
7. Add the cream of tartar and beat on medium-high speed until the whites hold soft peaks. Slowly add the remaining 24 g/2 tablespoons sugar and beat on medium-high speed until the whites hold firm, shiny peaks. Using a rubber spatula, scoop about one-third of the whites into the bowl containing the batter and, with the rubber spatula, gently fold in to lighten the batter. Gently fold the remaining whites into the batter just until combined.
8. Pour the batter into the prepared pan, smoothing the top with an offset spatula.
9. Bake until a cake tester inserted into the center comes out clean, about 1 hour and 15 minutes.
10. Let cool in the pan on a wire rack. To unmold, run a paring knife around the inside of the pan to loosen the cake, release and remove the outside ring of the pan, then invert the cake onto the wire rack and peel off the parchment. (The cake will keep, tightly wrapped, in the refrigerator for up to 4 days or in the freezer for up to 1 month.)
11. To make the syrup: In a medium saucepan over medium heat combine the water, sugar, and bergamot juice and bring to a simmer. Simmer, stirring occasionally, until the sugar dissolves.
12. Remove from the heat and let cool completely.
13. Wash, dry, and reassemble the springform pan. With a long, thin, serrated knife, cut the cake lengthwise into five equal layers.
14. Place one layer in the bottom of the springform pan.
15. Place a saucepan of water over medium heat and bring to a simmer. Set a heatproof bowl over the water, taking care that the bottom of the bowl does not touch the water.
16. Add the chocolate and heat until halfway melted. Stir gently, remove from the heat, and let cool until it registers between 95F/35C and 115F/46C on an instant-read thermometer.
17. Remove the tea-infused cream from the refrigerator and strain through a fine-mesh sieve into a separate medium saucepan (if using tea bags, simply discard them).
18. Add the milk and place over medium heat.
19. Heat until it comes to just a boil, stirring occasionally.
20. In a separate bowl, whisk together the egg yolks and sugar.
21. Whisking constantly, pour one-third of the hot cream mixture into the yolk-sugar mixture, then add this mixture to the remaining cream. Stir constantly over medium heat with a wooden spoon until the mixture thickens and coats the back of a spoon.
22. Remove from the heat and pour through a fine-mesh sieve into a clean bowl and let it cool until it registers 140F/60C on an instant-read thermometer. This is your crme Anglaise.
23. Measure out 600 g/2 1/4 cups crme Anglaise and add to the chocolate in four or five additions, using a heatproof spatula and vigorous strokes to incorporate. The temperature of the mixture should not exceed 113F/43C, which is why the cream is added in several additions. The mixture may appear broken at first but should come together by the final addition of cream to be smooth and glossy.
24. Let cool slightly. With a handheld immersion blender, blend the ganache until completely smooth and uniform. (A whisk is also fine, but an immersion blender makes for an ultra-silky ganache that pours very nicely.) Use immediately.
25. Using a pastry brush, soak the cake layer in the pan with one-quarter of the bergamot syrup. With an offset spatula, spread a thin layer of ganache (about 1/4 in/6 mm thick) over the cake. Top with a second cake layer, soak with an additional one-quarter of bergamot syrup, and then spread with half of the marmalade filling. Top with a third layer and repeat the process, alternating with one more layer of ganache and one more layer of marmalade filling, soaking each cake layer well with syrup. Top with the final cake layer, soak with the remaining syrup, and refrigerate until the cake is firm, 1 to 2 hours, then dust with cocoa powder.
26. Remove the cake from the refrigerator 2 hours before serving to bring to room temperature. To store, cover tightly and keep in a cool place for up to 4 days.
27. Reprinted with permission from Tartine Book No. 3: Modern Ancient Classic Whole by Chad Robertson. Text copyright 2013 by Chad Robertson; photographs copyright 2013 by Chad Robertson. Published by Chronicle Books LLC.