Bûche de Noël au ChocolatChocolate Bûche de Noël

Soften the butter and divide the eggs for sponge and cream

• 1 Cut 250g unsalted butter for crème au beurre, or buttercream, into 1.5cm cubes, place in a bowl and soften at room temperature, 20–25°C.
• 2 For the biscuit, an egg-foam sponge, prepare 4 eggs: put 2 whole eggs in a bowl, then add the other 2 yolks to that bowl and their whites to a separate bowl.
• 3 For the cream, prepare 3 eggs: put 1 whole egg and the other 2 yolks in a small bowl; put the whites, about 60g, in another bowl for mushrooms.
• 4 Sift 25g cake flour and 25g cocoa together 2 times.
• 5 Line a 27×27cm sheet-cake pan with parchment and preheat the oven to 200°C.

Whip the cocoa sponge and spread in the pan

• 1 Add 70g sugar to the sponge whole eggs and yolks and beat with a hand mixer on high for 5–6 minutes until pale and thick.
• 2 Beat the sponge whites separately on medium speed. When the bubbles are fine and even, add 35g sugar in 2 additions and beat to a meringue whose peak tips bend slightly.
• 3 Sprinkle the sifted flour and cocoa into the yolk mixture and fold from the bottom with a flexible spatula until no dry flour remains.
• 4 Add the meringue in 2 additions and fold in the same way until white streaks disappear.
• 5 Pour into the pan and use a dough scraper to spread evenly into all corners, about 8mm thick.

Bake the sponge and roll warm in a cloth

• 1 Bake on the middle rack at 200°C for 9–10 minutes.
• 2 While the sponge bakes, wet a clean cloth, wring firmly, spread on the work surface and place 1 new sheet of parchment on it.
• 3 Take the sponge out of the pan, invert baked side down onto the paper on the cloth and gently peel away its original baking parchment.
• 4 Loosely roll from the near edge with the paper and cloth and set seam side down.
• 5 Leave rolled at room temperature until completely cool, at least 30 minutes, while making the mushrooms and cream.

Pipe meringue mushrooms and dry at 100°C

• 1 Open the oven door to lower its temperature and set to 100°C.
• 2 Beat the 60g mushroom whites on medium speed. When bubbles are fine and even, add 60g sugar in 3 additions, then beat on high until the peaks stand straight.
• 3 Sift in 40g powdered sugar and fold 10–15 times until the sugar is no longer visible.
• 4 Use a piping bag with a 10mm round tip to pipe 9 domed caps 3cm across and 8 conical stems 2cm high on a parchment-lined baking sheet.
• 5 Dust the caps lightly with 3g cocoa through a tea strainer.
• 6 Check the oven has cooled to 100°C, then bake the meringues for 90 minutes to dry them.

Make and cool the rum syrup

• 1 Heat 60ml water and 40g sugar in a small saucepan over medium heat. When the sugar dissolves and it boils, take off the heat.
• 2 Let cool slightly, mix in 15ml dark rum and cool to room temperature.

Cook syrup to 120°C, make pâte à bombe and melt chocolate

• 1 Heat 160g sugar and 80ml water in a small saucepan over medium heat. Brush sugar crystals from the sides with a water-dampened brush and cook to 120°C, checking with a thermometer.
• 2 While cooking the syrup, transfer the cream whole egg and yolks to a deep bowl and beat on high for 3–4 minutes until pale and thick.
• 3 Once the eggs are pale and thick and the syrup is at 120°C, keep the hand mixer running at medium speed and pour the syrup in a thin stream down the bowl edge, avoiding the beaters, to make pâte à bombe, eggs whipped with hot syrup.
• 4 After pouring, increase to high and continue beating for 8–10 minutes until the bowl bottom feels about body-warm, around 30°C.
• 5 MeanwhileWhile whipping after adding syrup, melt 120g couverture chocolate in a heatproof bowl over water at 50–55°C, stirring. Remove from the bath and stir occasionally as it cools to about 30°C.

Mix in butter and chocolate to finish the buttercream

• 1 While beating on medium, add 250g softened unsalted butter in 4 additions, mixing until incorporated after each.
• 2 Add the chocolate cooled to 30°C and mix with a flexible spatula until evenly colored.

Brush with syrup, spread cream and roll again

• 1 Unroll the cooled sponge with its cloth and brush all the rum syrup, about 110g, evenly over its upper surface.
• 2 Take 230g buttercream and spread evenly with an offset spatula, making a thinner layer along the final 2cm at the far edge.
• 3 Fold about 1.5cm of the near edge inward to form a core, then roll away from you while lifting the paper underneath.
• 4 Set seam side down, wrap with the paper and twist the ends closed.

Refrigerate the roll for 30 minutes

• 1 Refrigerate, still wrapped in paper, for 30 minutes.
• 2 Leave the remaining buttercream at room temperature.

Cut the ends, add a branch and make bark marks in the cream

• 1 After the meringues have baked for 90 minutes, break 1 meringue cap to check dryness. If dry inside, remove the baking sheet and cool; if damp, bake in additional 10-minute increments and check.
• 2 Unwrap the chilled sponge and cut about 1cm straight from each end to neaten. Cut another piece about 5cm long diagonally from one end.
• 3 Place the diagonal cut against the top of the main log, with its round cross-section facing up as a branch stump.
• 4 Reserve 1 tablespoon buttercream, about 15g, separately.
• 5 Spread the rest over the log and branch with an offset spatula, leaving both ends and the branch cross-section exposed to show the spiral.
• 6 Draw long lines from end to end with the tips of a fork to imitate bark.

Refrigerate the plated log for 60 minutes

• 1 Transfer the log to a long serving dish and refrigerate for 60 minutes.

Temper, assemble the mushrooms and finish with sugar

• 1 Take the log out of the refrigerator 30 minutes before eating and leave at room temperature.
• 2 Put a little reserved cream on each cap’s flat underside and insert a pointed stem to assemble 8 mushrooms.
• 3 Put a little cream on the mushroom bases and stand 3 on the log and 5 around it.
• 4 Dust lightly all over with 10g powdered sugar through a tea strainer and slice immediately.