Hazelnut yule log with praline buttercream

Preheat the oven to 150°C, gas mark 2. Grease only the bases of two 37cmx24cm baking trays and then line both with baking paper. Set aside.

To make the sponge, sift the all-purpose flour, 50g cocoa powder, baking powder and 1 tsp salt together. Melt and cool the butter. Separate the egg yolks from the whites from 8 eggs, placing the latter in a large mixing bowl. Using an electric beater, beat the egg whites until soft peaks form, approx. 1 minute. Gradually add 130g of the caster sugar while continuing to mix until the meringue is thick and glossy and the sugar is completely dissolved. In a separate bowl, beat the egg yolks with another 130g caster sugar, 1 tsp vanilla extract and espresso at a high speed for approx. 5 minutes, until pale and thick. Using a spatula, fold half the meringue into the yolk mixture, then gently fold in the remaining meringue until just combined. Sift the dry ingredients again over the egg mixture and fold through gently until uniform. Drizzle over the melted, cooled butter and fold through carefully to maintain volume. Divide the batter between the two prepared trays and spread evenly. Bake for 10 minutes, or until the sponges spring back when gently pressed.

As soon as the sponges come out of the oven, cover each with a sheet of baking paper and aluminium foil. Let it sit for 5 minutes. Invert the sponge onto a board, peel away the base baking paper and roll it up tightly (peel off the baking paper just to unstick it, then place it back on the cake and roll it up again to form the shape) from the short end. This prevents sticking and helps shape the roll. Allow to cool completely at room temperature.

To make the hazelnut praline, place 225g caster sugar in a saucepan over a medium heat and allow it to melt without stirring. Swirl the pan occasionally until the sugar turns golden. Add the hazelnuts and stir quickly to coat. Transfer to a lined baking sheet and let it cool completely. Once cooled, break into small pieces and blitz in a food processor or high-speed blender until smooth and creamy. Set aside.

To make the buttercream, separate the egg yolks from the whites of 3 eggs. Fill a saucepan with a few centimetres of water and bring to a gentle simmer. In a glass or metal bowl, combine the egg whites and 225g caster sugar. Place the bowl over the saucepan and stir constantly with a whisk (do not aerate). Heat until the mixture reaches 60°C on a sugar thermometer or feels hot to the touch. Remove from the heat and allow to cool to room temperature. Meanwhile, in a stand mixer fitted with the whisk attachment, beat the unsalted butter until very pale and fluffy, approx. 8 minutes. Add half the egg white mixture and whisk until smooth, then add the remaining mixture. Mix in the 1 tbsp vanilla extract, praline paste, melted dark chocolate and salt. Beat until fully incorporated. Keep at room temperature until ready to use.

To assemble the yule log, carefully unroll each sponge. Spread a generous layer of buttercream evenly over each, then roll them back up tightly. Cut one roll in half diagonally to create two branches. Arrange the main roll on a serving platter and position the two cut pieces at an angle to resemble branches. Cover the entire log with the remaining buttercream. Using a fork, create a textured bark effect.

To decorate the yule log, shape small mushrooms from the marzipan. Pinch off small pieces and roll into balls. Flatten slightly, then use a paring knife to hollow out the underside. Roll matching pieces into short cylinders and attach them to the caps. Dust the mushrooms lightly with cocoa powder. Place the marzipan mushrooms on the log. Scatter the Oreo crumbs around the logs (for soil), pistachio powder (for moss) and berries.

Serve the yule log immediately.