For the biscuit base
60g caster sugar
2 tablespoons cocoa powder
1/2 teaspoon baking powder
For the filling
1 to 2 tablespoons double cream
100g crème de marrons (chestnut cream)
For the chocolate ganache
170g dark chocolate, finely chopped
125ml (1/2 cup) liquid cream
120g (1 cup) fresh cranberries
400g (2 cups) caster sugar, divided into 2
240ml (1 cup) water
1 egg white, at room temperature
2 tablespoons caster sugar
1/8 teaspoon cream of tartar (optional)
Pinch of salt
I - Make the sugared cranberries
- Up to 1 day before (I usually make these the night before), place the cranberries in a heat-proof bowl.
- Bring 200g (1 cup) of sugar and 240ml (1 cup) of water to a boil and stir until the sugar has dissolved. Remove from the heat and leave to cool for at least 5 to 10 minutes. Then pour the sugar syrup over the cranberries and let sit at room temperature or in the fridge overnight.
II - Make the meringue mushrooms
- Pre-heat oven to 90° Cover a large baking sheet with parchment paper.
- In a completely clean bowl of a stand mixer with the whisk attachment (or using an electric handheld mixer), whisk the egg white, cream of tartar and salt together on high speed for about 2 minutes.
- With the mixer running on high speed, add the sugar until stiff glossy peaks form - it should take another 2 minutes.
- Place in a piping bag fitted with a round piping top (or snip off the end of a ziplock bag), the pipe 8 to 10 round circles (these will be the mushroom tops) and 1 inch (3 cm) tall cones (these will be the stems). Using a moistened finger, gently tap to smooth down any peaks.
- Lightly dust the mushroom tops with cocoa powder.
- Bake for 2 hours. Remove from the oven and let cool completely.
- Melt a handful of chocolate chips in the microwave (melting in 15 seconds intervals on low power, stirring after each interval to avoid the chocolate seizing), then let the melted chocolate cool for a few minutes.
- When the meringues are completely cool, gently remove them from the baking sheet, spread a little bit of chocolate on the bottom of a mushroom top and stick a stem to it.
III - Make the cake
A. Prepare the cake batter
- Pre-heat oven to 180° Grease and line a rectangle baking pan with baking parchment. Grease the parchment paper too. Set aside.
- Separate the eggs into whites and yolks.
- In the bowl of a stand mixer (or with an electric whisk), whisk the egg whites with a pinch of salt until firm, about 4 to 5 minutes. Transfer into a separate bowl.
- In the bowl of the same stand mixer (no need to wash after taking the egg whites out), whisk the egg yolks and sugar together for about 6 to 8 minutes until thick and creamy.
- Sift the flour, cocoa powder and baking powder onto the egg yolk mixture and fold very carefully.
- Melt the butter and add to the mixture.
- Now fold the egg whites into the mixture very carefully - you don’t want to knock the air out.
- Pour the batter into the baking pan. Spread the batter evenly into the pan. Bake in the oven for 12 to 14 minutes or until the cake springs back when lightly poked with your finger. Don’t over-bake the cake as it will crack if over-baked.
- Place a clean tea towel flat on the counter. Once the cake comes out of the oven, immediately invert it into the tea towel. Peel off the parchment paper, then starting with the narrow end, begin tightly rolling the hot cake up with the tea towel. Do this slowly and carefully. Leave the cake to cool completely while rolled up in the tea towel.
- Beat the mascarpone, liquid cream and crème de marrons together until the ingredients are combined and the cream holds its shape.
- When the cake is completely cool, gently unroll the cake, spread the cream over the top (leaving a border on either side so the cream doesn’t come out when you roll it again), then carefully roll up again into a log. Cover with plastic wrap and refrigerate for at least 30 minutes (and up to 2 days) before shaping and topping with ganache.
- Remove the rolled log from the fridge. Cut a thick diagonal slice from one end of the log. Lift the log onto a plate or serving platter, then arrange the slice on the side with the diagonal cut against the cake to make a branch.
- Take the ganache out of the fridge and spread over the log and branch (don’t cover the end), then use a fork to mark the ganache to give the effect of tree bark.
- If using, arrange the sugared cranberries, rosemary sprigs, and meringue mushrooms.
- Leftover cake can be kept in an airtight container in the fridge for up to 3 days.