Collapsing chocolate cake

This cake is a thing of beauty, despite all its broken parts. Its name comes from the moment you remove it from the oven, then drop it – on purpose – to cause the middle of the cake to collapse in on itself. This cake is flourless and made super light by folding the whisked egg whites through the batter, which means it's both crunchy and soft, much like meringue. Complete with crisp edges, an almost custard-like middle and just enough coffee and vanilla to bring out the notes of the dark chocolate, it’s the cake of my dreams. Make sure to bake it on a low shelf in your oven, as this baby blooms like a soufflé when it cooks, so it needs space to rise. You can serve it plain, but I love filling the middle with whipped cream and fresh berries.

Ingredients: 

• 150g (1¼ sticks) salted butter, cut into pieces, plus extra for greasing
• 250g (9oz) 70% plain (semi-sweet) chocolate, broken into pieces
• 1 tsp vanilla extract
• 120ml (½ cup) strong cold coffee
• 220g (1 cup plus 3 tbsp) caster (superfine) sugar
• a pinch of sea salt
• 4 eggs, separated
• 200ml (scant 1 cup) double (heavy) cream
• 1 tsp icing (confectioners’) sugar, plus extra for dusting
• a mix of fresh fruit, such as raspberries, blackberries and cherries, to decorate

Method: 

Heat the oven to 160°C fan (350°F/Gas 4). Line the base and sides of a 16cm (6½in) springform cake tin with baking(parchment) paper. The paper should sit above the sides of the tin; use the leftover butter on the wrapper to help stick it.

Melt the butter and chocolate together in a double boiler or heatproof bowl set over a pan of gently simmering water, stir to combine, then pour into a large mixing bowl. Stir in the vanilla, coffee, sugar and salt. Let the mixture cool for 10 minutes or so; don’t worry if it looks split – I promise it’s all good.

As the chocolate mixture cools, whisk the egg whites in a clean,grease-free mixing bowl with an electric hand whisk until they form stiff peaks. Set aside.

Using the same electric whisk, mix the egg yolks into the melted chocolate, one at a time, until the mixture looks like a thick custard. Spoon one-third of the egg whites into the chocolate and briefly blitz with the electric whisk to loosen the mix. Fold in the rest of the egg whites with a metal spoon, keeping as much lightness and air in the cake batter as possible.

Gently tip the cake batter into the lined springform tin and bake on a low shelf for 40 minutes, until risen like a soufflé; the centre will be soft and gooey, but the sides should be crisp.

Now, this next step may go against all reasoning: take the cake out of the oven, lift it in its tin then drop from a 5cm (2in) height onto your work counter. This will force the middle of the cake to collapse evenly as it cools and create the perfect bowl-like shape for the whipped cream and berries. Leave the cake to cool completely in the tin, then chill for a firmer, fudge-like texture or keep at room temperature for a gooey, soft inside.

When you’re ready to serve, whip the cream with the icing sugar until light and fluffy. Spoon the whipped cream into the middle of the cake, pile the berries and cherries on top and dust with a little extra icing sugar, if you like.