Ingredients

Step by step

1. Preheat the oven to 180°C, fan 160°C, gas 4. Grease a 20cm round springform cake tin (at least 6cm deep) with oil and line the base and sides with baking paper, so that the paper rises above the sides of the tin.
2. For the sponge, use an electric hand mixer to beat together the butter and sugar until light and fluffy. Add the whole eggs and yolk, one at a time, beating well after each addition. Sift over the flour and baking powder, add the salt, then fold in until combined. Transfer to the prepared tin (it will be a shallow layer), level the top and bake for 25-30 minutes, until a skewer inserted comes out clean and the cake feels springy to the touch. Remove from the oven and set aside for about 5 minutes, then brush 2 tablespoons of whisky over the top of the cake while it is still hot. Set aside and leave to cool completely in the tin.
3. Meanwhile, leave the oven on for the oats. Line a baking tray with baking paper. In a small saucepan, melt the butter and brown sugar together over a low heat, stirring occasionally. Remove from the heat, add the oats with a small pinch of salt and stir to combine. Spread out on the prepared tray and bake for 20-25 minutes, stirring halfway, until golden and crisp. Set aside to cool completely.
4. For the mousse, put the frozen raspberries, sugar, 75g honey and 1½ tablespoons of whisky in a large saucepan. Set over a medium heat and slowly bring to a simmer, stirring occasionally, until the sugar has dissolved and the raspberries have broken down (15-20 minutes). Remove from the heat and whizz to a purée using a stick blender (or transfer to an upright blender). Put the gelatine leaves in a bowl of cold water and leave to soak for 5 minutes. Meanwhile, return the purée to a low heat. Squeeze the water from the gelatine leaves and stir them into the purée, off the heat, until dissolved. Strain into a large bowl, discarding the raspberry seeds, and leave to cool completely (1-2 hours at room temperature).
5. In another large bowl, whip the double cream and lemon zest to almost soft peaks. Using a balloon whisk, carefully fold the cream through the cooled berry purée until smooth and combined. Pour over the sponge base, smooth over the top, then chill in the fridge for at least 6 hours, preferably overnight, until set.
6. To serve, release the mousse cake from the tin and transfer to a flat serving plate. Carefully peel off the baking paper collar. Whip 150ml cream with 1 tablespoon of honey until thickened to almost soft peaks, then briefly whisk in 1 tablespoon of whisky. Spoon on top of the mousse cake, then top with the fresh raspberries and some of the caramelised oats. Enjoy any remaining oats alongside.