Chocolate charlotte

Method

1. Preheat the oven to 160°C. Line two baking sheets with baking parchment.
2. Put the egg whites and cream of tartar in the large bowl of a stand mixer (or use a large mixing bowl and an electric hand-held whisk) and whisk until frothy, then add half the sugar in small additions, whisking until stiff peaks form. In a separate bowl, whisk the egg yolks with the remaining sugar until pale. Gently fold the whisked egg whites into the egg yolk mixture, then gradually fold in the flour to make a smooth, airy mixture.
3. Fill a piping bag fitted with 2 cm plain nozzle with the mixture. Pipe fingers 9 cm long, leaving space between each as they will expand during baking. Dust with icing sugar and bake for 10 minutes, until lightly golden around the edges. Leave to cool on the sheets.
4. To assemble, sprinkle a little icing sugar onto the base of a 20 cm springform cake tin. Stand the lady fingers vertically around the edge, so each one is just touching the next. Refrigerate.
5. Place the chocolate and a quarter of the cream in a heatproof bowl set over a pan of barely simmering water, making sure the bowl is not touching the water. Allow the chocolate to melt, stirring occasionally. Put the remaining cream in the bowl of a stand mixer fitted with the whisk attachment (or in a mixing bowl and use a hand-held electric whisk) and whisk it till barely thickened
6. Add the chocolate ganache to the thickened cream and stir to combine. Pour the mixture into the tin, inside the lady finger border, and put back in the fridge to set.
7. Once set, remove the sides of the tin. Tie a ribbon around the base if you wish. Dust with cocoa powder and add any decorations you like, such as berries, whipped cream or edible flowers.