Preheat the oven to 200°C (or 180°C if using a fan) / 400°F and grease two 6 oz tart pans with butter, as if you were making a sacred pact with them. Grease them well, we don't want any betrayals. And if you really want to ensure peace, sprinkle a little cocoa powder on top - no rebellion that way!
Melt the dark chocolate and butter in a bowl over a saucepan of simmering water, stirring occasionally, as if conducting a perfect waltz. When everything is melted and silky, let it cool down a little.
With an electric mixer, beat the egg, egg yolks, icing sugar and vanilla until the mixture is so thick and pale yellow it could be the star of a baking commercial. Make sure it has doubled in size, like a good little thing that just won't stop growing.
Add the salt, flour and melted chocolate to the egg mixture, and mix carefully, as if you were protecting a house of cards. Keep as much air as possible in the dough, which is its soul. And don't forget to scrape the bottom of the bowl well; flour is not shy, but it loves to play hide-and-seek.
Spoon the batter into the moulds and place a couple of pieces of white chocolate on top (see the image in the previous post for visual inspiration). Don't squish them like a spelling mistake, and resist the temptation to cover them with more batter. Trust, the white chocolate will work its magic and melt in the oven, word of dessert.
Bake for 12 minutes, or until the cakes are well browned on the outside, but retain a slightly moist texture in the centre. Leave to stand on a wire rack for 5 minutes to set, then carefully invert onto a plate. If necessary, run a knife around the edges to ensure perfect moulding. Serve immediately with quality vanilla ice cream, fresh raspberries and a subtle touch of raspberry sauce to complement the tartness.