Chocolate and hazelnut yule log with meringue mushrooms

Make the meringue mushrooms at least 1 day before you want to serve the yule log. Preheat the oven to 120°C. Whisk the egg whites to soft peaks, then whisk in the cream of tartar. Add the caster sugar 1 tablespoon at a time, whisking continuously until you have added half of the sugar, then slowly pour in the remaining sugar, whisking continuously until the sugar has fully dissolved and you have reached stiff glossy peaks

Line 2 baking trays with baking paper, securing the paper down with a small blob of meringue in each corner

Transfer the meringue into a piping bag and snip the end 5mm wide. Pipe small domes in a range of sizes for the mushroom caps and thin straight lines for the stalks. Bake for at least 1 hour, until completely dry and the meringues easily peel off the baking paper. Turn off the oven and leave the meringues inside to cool completely with the door ajar (overnight works well). Once completely cool, carefully transfer the meringues to an airtight container

Preheat the oven to 200°C. Grease and line a 23cm x 33cm baking tray with baking paper

For the sponge, whisk the eggs and caster sugar in a large bowl with an electric whisk for 5 minutes until pale, thick and tripled in volume (you can do this in a stand mixer if you prefer). Sift the self-raising flour and cocoa powder into a bowl and whisk to combine. Gently fold through the egg mixture until just combined and there are no pockets of flour

Gently pour the mixture into the prepared tin and spread into an even layer. Bake for 8-10 minutes, until risen and springy to the touch

Place a sheet of baking paper on a work surface and sift over some cocoa powder. Carefully and confidently flip the tin over onto the cocoa powder, then peel off the paper used for baking. Whilst hot, score a line 2.5cm from the edge of the long side nearest you half way into the cake then, using that edge, roll up the cake including the paper and leave to cool

For the hazelnut filling, melt the butter in a small saucepan over a medium heat and cook for 5 minutes until the milk solids caramelise and the butter smells nutty. Pour into a heatproof bowl to stop the cooking

Toast the hazelnuts on a baking sheet for 8-10 minutes, until golden and fragrant, then leave to cool slightly. Reserve 20g for garnish

Warm half of the cream with a pinch of salt in a small saucepan until steaming

Blitz the 100g of the hazelnuts in a small food processor until they form a smooth paste, scraping down the sides as needed – this will take a few minutes

With the motor running, gradually add the white chocolate, followed by the warm brown butter and cream. Blend until completely smooth and glossy then transfer to a bowl and cover the surface with cling film to stop it forming a skin. Chill for 30 minutes

For the cranberries, place all of the ingredients except the cranberries in a small pan with a pinch of salt. Bring to a simmer, stirring occasionally until the sugar has dissolved

Add the cranberries and cook for 5 minutes, until softened but still holding their shape (if using frozen cranberries they will need a couple of minutes longer). Remove from the heat and leave to cool in the syrup. Set aside in an airtight container until needed (you can do this the day before if you prefer)

To finish the meringue mushrooms, melt the dark chocolate in a bain-marie and use a little to attach the meringue mushroom caps to their stalks. Set aside to set

Whip the remaining double cream for the filling to soft peaks. Beat the chilled hazelnut mixture briefly to loosen, then gently fold through the whipped cream until light and spreadable

To assemble, carefully unroll the cooled sponge and spread evenly with the hazelnut filling, leaving a small border around the edges. Roll the sponge back up tightly, using the baking paper to help you. Set aside

For the ganache, place the dark chocolate in a heatproof bowl. Heat the double cream with a pinch of salt until steaming, then pour over the chocolate and leave for 30 seconds. Use a spatula to stir from the middle of the bowl (the mixture will draw cream in from the outside in – this is called localised stirring) Leave at room temperature for at least 10 minutes, until in has cooled slightly and is thick enough to spread

Trim the ends of the log and cut one end at an angle and position the piece against the side of the log to create a branch, securing it with a little ganache

Spread the remaining ganache over the log, using a palette knife to create rough bark-like ridges. Arrange the mushrooms on and around the log

Drain the cranberries from their syrup, and roughly chop the reserved hazelnuts. Arrange both in small clusters on and around the log