===== Tools ===== 2 9x2-inch (23 cm) round cake pans stand mixer with 7 qt work bowl small saucepan pastry brush assorted work bowls 4 or 5 cardboard cake rounds offset spatula cake strips (optional) long bread knife =========== Cake layers =========== 225 g unsweetened chocolate 2 tbl softened butter, for pan prep 1/2 tbl orange extract 1 tbl freshly grated orange zest (approx. 2 oranges) 12 extra-large eggs, room temperature 390 g superfine or caster sugar 2 tsp vanilla extract 110 g Dutch process cocoa powder, sifted (up to 1/3 black cocoa) plus 1 tbl 260 g pastry flour, plus 2 tbl 1 tsp baking powder 1 tsp ground Ceylon cinnamon 1/2 tsp ground mace 1/4 tsp freshly ground nutmeg 1) Place the unsweetened chocolate in a microwave-safe bowl and zap on high in 15-second intervals, stirring each time, until fully melted and smooth. Set aside to cool. 2) Liberally butter two 23 cm (9"x2") round cake pans. Sift together 2 tbl pastry flour and 1 tbl cocoa powder and use the mixture to coat the entire inside surface of the pans. Position a rack in the middle of the oven and preheat to 350 F/175 C. 3) Using a mortar and pestle, grind orange extract and orange zest together until smooth. 4) Sift together the dry ingredients and set aside. 5) In the bowl of a stand mixer, combine eggs, sugar, vanilla, and orange zest paste. Whip using the whisk attachment on medium-high until light in color and foamy, 10 to 20 minutes. 6) Gently transfer the egg foam to a large, wide-mouthed bowl and fold in a third of the dry ingredients (should be about 130 g). Then fold in half of the melted and cooled chocolate (110 g). Fold half of the remaining dry ingredients, the remaining chocolate, and then the last of the dry ingredients. Do not over-mix. The egg foam will deflate substantially during this process, but there should still be lots of small bubbles. 7) Divide the batter into the two prepared cake pans. Lightly tap each pan to release any large trapped bubbles, then smooth the top with a spatula. Apply wet cake strips to each pan, if you have them. Bake the layers until a cake tester comes out clean (start testing at 20 minutes), rotating the pans halfway through. 8) Cool the cakes in their pans on a wire rack for 15-20 minutes, then carefully depan and cool completely, at least 60 minutes. 9) Using a long bread knife, level the tops of the cakes. You can eat the scraps, or grind them into crumbs to use for another recipe. 10) Using a piece of parchment or waxed paper to keep them separate, stack the cakes on top of each other, the tops touching, and rotate the top cake until you find a pleasing orientation. Cut a witness mark (vertical notch) into the side of the stacked cakes to help line them up later. 11) Using a long bread knife, slice the two cooled cakes in half, making four layers in total. You may find it easier to put the cakes on a turntable, score the entire circumference while holding the knife level, and then cut all the way through. 12) Arrange the layers cut-side-up on cardboard cake rounds and cover until ready for the next step. ============= Soaking syrup ============= 100 g superfine/caster sugar 160 ml water 60 ml Courvoisier cognac 1) In a small saucepan, combine sugar and water. Heat on medium until boiling, then let boil for 5 minutes. Allow to cool to about 130 F/55 C. 2) Whisk in cognac until completely combined. Allow to cool to warm room temperature. 3) Using a pastry brush, paint the cut sides of the cake layers with the syrup. Do not skimp: use all of the syrup. 4) Place the soaked layers in the freezer until ready to fill the cake. ============================================== Cognac-flavored "American buttercream" filling ============================================== 360 g confectioner's/powdered sugar 150 g unsalted butter 2 egg yolks (use pasteurized eggs if serving vulnerable ppl) 60 ml Courvoisier cognac 1) In a stand mixer fitted with the paddle attachment, beat together all of the ingredients until smooth and fluffy. You should end up with about 580 g in total; you will only need 480 g. 2) Put a small dollop of frosting in the center of a cardboard cake round. Place the bottom layer of the cake, cut side up, onto the round; twist and press firmly to seat and fully adhere the layer to the cardboard. 3) Place the cardboard round on a turntable or cake stand. Using an offset spatula, apply 160 g of the filling to the top only of the first layer. 4) Line up the notch on the second layer over the first, cut side down, twist to align, and press firmly to seat. 5) Repeat this process twice more for the remaining layers. Use any remaining frosting to fill in any gaps between the layers that become apparent after filling. Cover the cake in plastic wrap and refrigerate until ready to frost. ===================================================== Gianduja flavored Swiss meringue buttercream frosting ===================================================== Based on Joanne Chang's milk-chocolate Swiss meringue buttercream from Flour's Midnight Chocolate Cake. This recipe will make quite a lot more frosting than you need, about 1400 g, which should be enough to frost two cakes. Leftover buttercream can be stored in the refrigerator for about a week, or frozen nearly indefinitely. For this reason, this part of the recipe can be made ahead. After storing, bring completely to room temperature (may take several hours) and beat using the paddle attachment of your mixer until smooth and fluffy, 1 to 2 minutes. Note: Valrhona makes two different gianduja formulas: Noisette Lait, which is about 35% hazelnuts and only 4% cacao solids, and Noisette Noir, which has 36% cacao but no dairy. I've tested both; you definitely want the Noisette Noir. (There's plenty of dairy in this buttercream anyway; you won't miss it, and the color is vastly better with the Noir.) 350 g Valrhona Noisette Lait gianduja, cubed 120 ml heavy cream 300 g sugar (superfine/caster sugar is best but granulated works) 3 large egg whites, at room temperature 680 g (6 US sticks) unsalted butter, cut into ~30g chunks, at room temperature 1/4 tsp kosher salt 30 ml (2 tbl) Courvoisier cognac (replaces vanilla in original recipe) 1) Place the chopped gianduja in a small heatproof bowl. In a small saucepan, scald the cream (do not let it boil). Pour the hot cream over the gianduja and let stand for 1 minute. Whisk slowly until smooth, then let stand at room temperature until cool, about 15 minutes, stirring occasionally to keep it from separating. Stir in the salt. 2) Set water to simmer in a saucepan. In a heatproof bowl that just fits over the mouth of the pan, whisk together the sugar and egg whites. Set the bowl over the simmering water and let heat until hot, 4 to 8 minutes, whisking frequently. The egg mixture should reach a temperature of 160 F/70 C as measured with a probe thermometer. 3) Empty the egg mixture into the bowl of your stand mixer. Using the whisk attachment, beat the egg whites on medium-high until a tepid, fluffy white meringue is formed, 10 to 20 minutes. Keep beating until the temperature of the meringue drops below 90 F/32 C; this is important for the next step as you do not want the butter to break when you add it to the meringue. 4) Reduce the mixer speed to low and add the soft butter, a couple of chunks at a time. When the butter is no longer visible, add more, a chunk or two at a time. When all the butter is added, stop to scrape the bowl, then increase speed to medium and whip for 2 to 3 minutes, until smooth. Scrape the bowl again. 5) Swap in the paddle attachment to your mixer, and with the mixer running on medium, slowly pour in the cooled gianduja ganache. Add the cognac. Continue to beat on medium until smooth and uniform, about 1 minute. ~~~~~~~~~~ At this point, you can cover tightly with plastic wrap and refrigerate. Once fully cooled, the buttercream can be frozen. Before using, it must be brought up fully to room temperature and whipped again to regain fluffiness. Warning: you may find it hard to resist eating the frosting while it's warming on the counter -- it's mostly solid butter and chocolate! ~~~~~~~~~~ 6) Remove the cake from the refrigerator. Using an offset spatula, apply a thin layer ("crumb coat") of frosting to the sides of the cake, filling in any gaps. Return the cake to the refrigerator for another half an hour. 7) Beat the remaining frosting on medium for a minute to restore its fluffiness. Using an offset spatula, apply frosting to the top and sides of the cake until it is coated in an even layer (how thick you want it to be is up to you). Make certain that the top is absolutely smooth, as the glaze will magnify imperfections. Return the cake to the refrigerator until the frosting is completely set. ============================ White chocolate mirror glaze ============================ For this part of the recipe, you can follow Diane Duane's original formula (white chocolate cream cheese sur-frosting) or you can apply a white chocolate mirror glaze. Most mirror glaze formulas make enormous quantities (appropriate for a commercial bakery) and/or use gelatin (made from pigs' feet); in my research, I found one formula which uses agar agar instead of gelatin, so I could have a vegetarian (and kosher-dairy) version: https://www.gretchensbakery.com/mirror-glaze-recipe-vegetarian-version/ This recipe makes about 1 kg before straining, 825 g after straining; in testing I used about 430 g but after service I felt that was too much. Also, when I made it, the ultimate color was an unattractive tan, which did not respond well to food coloring; I'm not sure if this is a result of using unbleached sugar, or an issue with the agar flakes I had to use instead of powdered agar. Next time I'll try doing the non-vegetarian version and use a more refined sugar. It's generally recommended to freeze your cake before applying mirror glaze. I couldn't do this because the cake was too tall to fit in my freezer drawer.