Serves: 24 cakes1) Preheat the oven to 170C/Gas 3. Line the cups of a 24-cup cupcake tin with paper baking cases.
2) Whisk together the buttermilk, oil, vanilla and eggs. Combine the sugar, flour, cocoa powder, bicarbonate of soda, baking powder and salt and add into the wet mixture. Whisk the batter together until almost all the lumps are gone. Scrape the bowl, then mix again briefly. Add in a small amount of the port wine to help thin the batter. Once it is incorporated, slowly add in the remaining wine, whisking continuously.
3) Scrape the bottom of the bowl and make sure that there are no lumps. Scoop the batter into the prepared paper cake cases using a number 16 scoop. Bake until a cocktail stick inserted in the middle of a cupcake comes out clean, about 25 minutes.
4) Allow the cupcakes to fully cool. Using an apple corer, remove a piece of the cupcake from the centre. Drizzle with 1 tsp of port wine reduction syrup. Fill the cupcake with 1 tsp raspberry creme fraiche filling. Using a large star tip, pipe the chilled French chocolate mousse onto the cupcake. Garnish with the gold leaf flake.
To make the port wine reduction syrup:
Combine the wine, sugar and salt in a saucepan over a low flame. Simmer until reduced to 42g liquid.
To make the raspberry creme fraiche filling:
Whisk the creme fraiche with the raspberry preserves to combine.
To make the French chocolate mousse:
1) Place the chocolate and butter in a heatproof bowl and place over a saucepan containing barely simmering water (or use a double boiler). Melt the chocolate and butter together and stir with a wooden spoon until smooth.
2) Remove from the heat and cool slightly. Add the egg yolks to the chocolate, 1 by 1, beating with a whisk until incorporated. Set aside.
3) In another bowl, beat the egg whites until foamy. Add the cream of tartar and continue to beat. Gradually whisk in 50g of the sugar and continue beating until stiff peaks form.
4) Beat the double cream in a chilled bowl until it begins to foam and thicken up. Add the remaining 2 tbsp sugar and the vanilla. Continue to whip the cream until it holds soft peaks.
5) Gradually and gently fold the egg whites into the chocolate mixture to lighten it. Then, delicately fold in the whipped cream. Take care not over work the mousse.