Preheat the oven to 180°C/160°C Fan (350˚F). Lightly grease a 20 cm (8 in) round springform cake tin (pan) and line the base and sides with baking parchment.

Melt the chocolate and butter in a bain-marie (see below). Remove from the heat and set aside to cool slightly. Put the egg yolks and brown sugar in a large bowl set over a pan of simmering water and, using an electric hand mixer, whisk for 2–3 minutes or until the mixture is pale and thick. remove the bowl from the heat, pour in the chocolate mixture and fold together to combine.

Working quickly, wash the beaters of the mixer. Put the egg whites, caster sugar, cream of tartar and salt in another large bowl and whisk until the meringue holds soft peaks. Fold a third of the meringue into the chocolate batter, then the remainder in two additions, folding gently until the mixture is streak free.

Pour half the batter into the prepared tin, spreading gently into an even layer. Bake for 25–30 minutes or until risen and domed on top. remove and allow to cool for 10 minutes. during this time the centre of the cake should cave in on itself a little. If it stays level, use a spoon to lightly compress the cake, creating a slight well. Scrape the remaining batter over the cake and gently spread into an even layer. Bake for 15 minutes. The top layer will remain very soft but it will have formed a thin crust.

Leave to cool to room temperature before transferring to the refrigerator and leaving for at least 6 hours, but preferably overnight.

To make the crème anglaise, pour the cream and milk into a saucepan. Grate about a third of a single nutmeg into the pan, stir to combine, then bring the mixture to a simmer over a medium heat. Meanwhile, put the egg yolks, vanilla and sugar in a mixing bowl and whisk until pale. Pour over the cream mixture, whisking as you do so, to prevent the eggs from scrambling. Pour the custard back into the saucepan, place over a low heat and cook, stirring constantly, until the custard thickens enough to coat the back of a spoon. To ensure the custard is fully cooked it needs to reach between 75 and 80°C (167 and 176˚F). Pour the custard into a jug, cover with cling film (plastic wrap), to prevent a skin from forming, and refrigerate until thoroughly chilled, at least 2 hours. You can also serve the custard warm, but I absolutely love it cold, so this is my preference.

To serve, carefully un-mould the cake, very gently peel away the parchment from the sides, and dust with cocoa powder. To get the cleanest slices, dip a knife in very hot water, wiping it dry with a kitchen cloth after each slice. serve the slices in a puddle of the crème anglaise.

The cake can be refrigerated for up to 3 days.

Notes

You can also use a 23 cm (9 in) springform tin (pan) if that is what you have, but you’ll end up with less-defined layers.

As the recipe does use a lot of eggs, you could skip making the custard, simply infuse the same amount of nutmeg into 600 ml (20 fl oz/2½ cups) whipping (heavy) cream and refrigerate until needed, using as a sauce or whipping to soft peak.

Baine-marie

Finely chop the chocolate to ensure even melting.

Stir often to ensure even melting.

Keep both the water level and the heat low. The water should never be allowed to touch the bowl and the heat should similarly be kept low, so the chocolate doesn’t become too hot.

Wipe the bottom of the bowl with a towel once the chocolate is melted, to remove the risk of water contaminating the melted chocolate.