Week 67: Bûche de Noël 2015 – chocolate sponge roll filled with chocolate and hazelnut mousse on a hazelnut shortbread crust

Christmas is definitely my favourite festive season of the year and to commemorate the holidays this year I decided to try my hands at baking a Yule log. I didn’t want it to be just any standard chocolate Swiss roll. But since I love everything chocolate I know it has to have chocolate, and lots of it! After doing a bunch of recipe research, I decided on a basic chocolate sponge, filled with chocolate mousse, sitting on a shortbread crust. As there are a few components, I would suggest making this over the span of a few days.

Makes a 8.5” log

INGREDIENTS

For the chocolate sponge

3 large eggs

55g cake flour

15g Cocoa powder

80g granulated white sugar

30g unsalted butter

40g whole milk

1.5 tsp sweetened condensed milk

1 tsp pure chocolate extract

40g milk chocolate couverture, melted

For hazelnut shortbread

70g raw hazelnuts

80g light brown sugar

130g all purpose flour

12g cornstarch (corn flour)

½ teaspoon salt

113g unsalted butter, room temperature

¾ tsp pure vanilla extract

40g dark chocolate couverture

15g feuilletine crunch

For the chocolate ganache

200g dark chocolate couverture

200g heavy cream

70g unsalted butter, cubed, at room temperature

DIRECTIONS

1) Heat up milk and butter in a saucepan until butter is completely melted. Set aside to let cool to room temperature.

2) Whisk together cake flour and cocoa powder.

3) In the stand mixer with the whisk attachment, beat the eggs, sugar and sweetened condensed milk until the ribbon stage and until it has tripled in volume.

4) Sift the dry ingredients into the egg mixture in 3 stages and fold in with a quick but careful hand, and make sure not to deflate the eggs too much.

5) Add 2 tablespoons of the egg mixture and the chocolate extract to the cooled butter and milk and stir to combine. This helps to lighten the butter mixture.

6) Pour the butter mixture carefully back into the egg mixture and fold until just combined.

7) Line a 9” x 13” sheet pan with parchment paper at the bottom of the tin and carefully pour the batter. Smooth it out and ensure batter reaches all corners of the cake tin.

8) Bake at 170C (fan) for 12 to 15 minutes until you hear a “pffff” sound when pressed lightly with a finger, and until the sponge springs back when pressed. The sides of the cake should start to pull away slightly from the cake tin.

9) Line another parchment paper lightly with some sifted cocoa powder. Then, run a knife around the egg of the cake and turn the cake out onto the cocoa powder-lined parchment paper. Remove the parchment paper carefully from the bottom (now top) of the cake.

10) Cut out across the short end of the cake, an approximately 9” by 9” square portion. Transfer this square cake, together with the parchment paper below, onto a sheet of plastic transparency, which you will use to bend the cake into a “U”-shaped block. This will be the main body of the log. Sandwich the cake on the plastic sheet between 2 heavy objects (I used 2 boxes) to let it cool to room temperature.

11) Use the remaining portion of the cake to shape two filled “U” pieces to cover the 2 ends of the main log body.

12) When cake has cooled to room temperature, generously cover the top of the square piece with a coating of the melted milk chocolate. Then, coat one side of each of the “U” piece with the melted chocolate and stick it onto each end of the log, to form a container which will be filled with the chocolate and hazelnut Bavarian cream.

13) Transfer the entire cake, together with the 2 sandwiching objects, into the freezer and let it set overnight. You will need a decent space in the freezer for this, so make sure you set aside the space beforehand.

14) When the cake has set, you can remove the plastic sheet and sandwiching objects. Prepare the chocolate and hazelnut mousse using the Bavarian cream in this recipe. There is more than enough mousse to fill the log cake cavity, so you can set the remaining mousse in any jars or muffin tins. I filled half of the cavity with the hazelnut mousse, and the other half with the chocolate mousse. After filling, return the log cake to set in the freezer overnight.

15) To make the hazelnut shortbread, preheat oven to 180C. Place rack in center of oven. Lightly butter your baking tray (I used 9” x 13”) then line with parchment paper.

16) Place hazelnuts on a baking sheet and bake for approximately 15 minutes or until brown and fragrant and the skins start to peel. Remove from oven, place the warm hazelnuts in a clean dish towel, roll it up, and let the nuts steam for 5 minutes. Briskly rub the nuts to remove most of their skins. Set aside to let the nuts cool.

17) Place the hazelnuts and 15g of the brown sugar in a food processor and pulse until the nuts are finely chopped.

18) In a small bowl combine the flour, cornstarch and salt.

19) In bowl of electric mixer, or with a hand mixer, beat and butter and remaining brown sugar until smooth. Add the vanilla extract and beat until combined. Add the flour mixture and beat until incorporated. Stir in the nut mixture.

20) Measure the length and width of the base of your log cake, mine was about 8.5” by 3”. Roll out the shortbread dough. Add a little flour to the surface of your workspace if dough is too sticky. Then cut out the rectangle and place it on the prepared baking tray. (You can freeze the remaining cookie dough or just cut it into your favourite shapes and sizes.) Freeze the shaped dough on the baking tray for at least an hour (I left it in the freezer for a day) then place in preheated oven and bake until deep golden brown, about 25 to 30 minutes. Transfer shortbread to a wire rack and let cool completely.

21) Prepare the feuilletine crunch layer by melting the dark chocolate couverture and adding the feuilletine. Coat the top of the shortbread with the feuilletine mixture, then immediately place the overturned log cake (inverted “U”) onto the coated shortbread.

22) To make the chocolate ganache, put heavy cream in a pot and bring to boil. Pour cream over chocolate couverture in a heat-proofed bowl and let sit for 5 minutes. Stir mixture, from center outwards until well-mixed and smooth. Add butter and mix well until fully incorporated. Cover the cake generously with the ganache and leave to set in fridge or freezer.

23) For the leftover ganache, allow it to cool in the fridge for around 30 minutes, then using the whisk attachment on a stand mixer, whip until ganache turns a lighter shade and is slightly voluminous. You can use this whipped ganache to pipe designs on top of the log cake.

Once, the ganache on the cake is set, lightly drag the tines of a fork along the log for decorations. I also made a quarter portion of the whipped cream from this recipe and piped it on the top of the cake, to lighten the taste.

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