Chocolate Truffle Cake
This intensely chocolate cake originated from an all-day baking session in my home kitchen with an old friend. We were working to recreate the rectangular Chocolate Tile Cake from a long-gone Greenwich Village restaurant, La Tulipe. The process presented many challenges, including maintaining even, straight lines during the assembly of the free-form rectangle, and shaping the chocolate tiles.
It occurred to me that we could assemble the same components–a flourless chocolate cake and whipped ganache–in a round cake ring to simplify the assembly process. The chocolate tiles would be replaced by chocolate shavings or a chocolate band for the trulyambitious.
And so, the Chocolate Truffle Cake was born–a rich, lovely chocolate creation with a velvety interior that marries beautifully with the soft cake.
For the cake, I used the much-loved Chocolate Souffl© Sheet, in a slightly bigger recipe than usual, baked in a half sheet pan. The chocolate truffle filling is a whipped ganache, which, instead of letting it set overnight like other classic ganache, is cooled for about two hours and then whipped just until it thickens.”
One of the keys to the chocolate truffle filling is the temperature of the ganache when it is whipped. After numerous tests, I determined that the ideal temperature falls between 72 °F and 73 °F. Another round of testing concerned the type of chocolate, and I settled on the 64%Guittard.
Like many cakes, this one can be assembled in stages. The Chocolate Souffl© Sheet can be baked the day before, and the circles cut and frozen. The chocolate shavings can be prepared and stored at room temperature or in the refrigerator.
I am extremely proud of this cake, which took form during a kitchen collaboration with a very talented pastry chef, a good friend of mine. All the testing and note-taking to perfect the whipped ganache filling paid off.
Chocolate Truffle Cake is best served at room temperature and can sit out for at least two days. If refrigerated overnight, remove it from the refrigerator for at least two hours before serving. As with many rich chocolate cakes, it pairs well with lightly sweetened whipped cream or vanilla sauce.
Chocolate Truffle Cake
| Yield: 1 8†cake | # of Servings: 12 to 14 |
Ingredients:
Chocolate Souffl© Sheet
8 oz (227 g) chocolate, 55% to 61%, wafers or broken up
3 tbl (1.5 fl oz) water
8 egg yolks
5 tbl (2.4 oz / 68 g) sugar
1 ½ tsp vanilla extract
8 egg whites
â…› tsp salt
½ cup + 3 tbl (4.8 oz / 136 g) sugar
Whipped Ganache:
2 ½ cups (20 oz) heavy cream
15 oz chocolate, 64%, wafers or chopped
Decoration:
Chocolate shavings:
1 large piece semi-sweet chocolate
Chocolate band:
6 oz chocolate, 55% to 61%, wafers or chopped
Dark cocoa powder, as needed for dusting
Tools and equipment needed:
- One 17.8†by 12.8†half sheet pan
- 8†by 2†stainless cake ring
- 8†and 9†cardboard cake circles
- Counter top or hand-held mixer
- Instant read thermometer
- Large (21†preferred) pastry bag with a 0.5†(Ateco 806) or 0.56†(Ateco 807) tip, or small offset spatula
- Small butane torch.
- Acetate strip, 25.1â€, if doing chocolate band
Pre-recipe preparations:
- Preheat oven to 375 °F
- Butter the cake pan and line with parchment circle, lightly butter the parchment.
Directions
Cake:
- Melt chocolate and water in large metal mixing bowl over a double boiler. Set aside.
- In machine bowl with whisk attachment on medium high speed (8 on a KitchenAid), or in mixing bowl with a handheld mixer, beat the egg yolks, sugar, and vanilla extract. Beat until thick and light colored, scraping down the sides of the bowl occasionally.
- Add yolk mixture into chocolate, stir to combine with plastic spatula. Be sure to scrape the bottom of the bowl to incorporate all the chocolate.
- In clean mixing bowl, with a clean whisk attachment beat whites on medium high speed (7 on a KitchenAid) with salt until soft peak stage. Slowly add the sugar and beat just until firm peaks. Do not overbeat.
- Add ¼ of the whites to chocolate mixture and stir to lighten. Fold in remaining whites just until the batter is homogenous, and no white streaks appear.
- Pour batter into prepared pan and spread evenly with an offset spatula.
- Bake for 12 minutes, just until the sheet is firm to the touch, and cake tester comes out clean.
- Remove to a cooling rack and cool in the pan until just slightly warm.
- Run a small knife or butter spreader around the edge of the pan.
- Dust the top of the cake with cocoa powder, and invert into a large cutting board or silpat.
- Using a cake ring, or cardboard circle cut two 8†circles, and as many 3†circles as possible,
- The cake is very fragile so be careful with the next step. Slide 8†cardboards under each cake circle. Wrap lightly with plastic film and set aside or freeze.
- Save the 3†circles in the freezer for individual cakes
Whipped Ganache:
- Place heavy cream in heavy saucepan. Bring just to the boil.
- Add the chocolate all at once, cover, and let sit for 10 minutes.
- Using plastic spatula to scrape the bottom of the pan, and a wire whisk, gently stir just until the ganache is smooth.
- Pour through a fine-mesh strainer into a clean container or machine mixing bowl.
- Let cool at room temperature of 1.5 hours, stirring every 15 minutes or so.
- Place ganache in refrigerator, along with a machine mixing bowl (if mixture isn’t in one) and the mixer whisk attachment.
- Continue stirring the ganache in 15-minute intervals, until it has cooled down to between 72 °F and 73 °F. Be sure to scrape the sides with a plastic spatula to maintain the ganache at a consistent temperature.
Assembling the cake:
- Place the stainless steel cake ring over one cake circle, with cardboard circle underneath it. Place on top of larger 9†or 10†cardboard circle.
- If using pastry bag, insert a 0.5†inch (Ateco #806) or a #807 tip and drape over quart container or measuring cup to facilitate filling.
- Using the wire whip attachment, whip the ganache just until it starts to stiffen, about 1 ½ to 2 ¼ minutes on med-high speed. Stop whipping when it appears to have thickened, and let it sit for a few seconds to test (see 3rd pic below). Do not overwhip or the ganache will get grainy.
- If using pastry bag, fill the bag with whipped ganache.
- Pipe or spread whipped ganache to fill just over ¾ of the cake ring.
- Place the second cake circle on top, and press gently. There should about ⅛†and ¼â€ space on top
- Pipe or spread whipped ganache and using a long metal spatula, level it out with the cake ring.
- Refrigerate to set for 10 to 15 minutes.
- Use a butane torch to warm the outside of the cake ring, and remove the ring.
- Press the chocolate shavings against the sides of the cake.
- Using a fine-mesh strainer, dust the top with cocoa powder.
- Serve at room temperature.
Notes:
1 A cake with any type of ganache may be left at room temperature for the same reason chocolate truffles are kept at room temperature. Scalding the cream before the chocolate is added kills the microorganisms that would cause the cream to spoil.
