On the short list of recipes I think any baker should have — or simply any person who delights in making their friends happy should have — is a chocolate cake to be thrown together just because… “well, actually I didn’t know today was your birthday. Of course I am free tonight!”

This cake should be tiny. In fact, if you were the kind of person who decided to plan ahead, you might invest in a 15cm cake tin, because the 15cm cake tin holds nearly exactly half the volume of batter (while keeping the same festive height) as a more standard 23cm tin and is the very best thing for small, last-minute gatherings (providing four generous or six tidy slices). You would walk out of the baking-supply store a better friend than you walked in; a 15cm cake tin brims with good intentions.

This cake is what I sent home with the babysitter when she let it slip that it was her birthday one day. It’s as simple to make as melting chocolate and beating eggs.

Many flourless cakes can feel leaden, like baked truffles, too intense for anything but nibbles — but this cake fights that in two ways: by lightening it as much as possible with the lift of whipped egg whites and by keeping the serving size so tiny that it’s really just right.

I round the edges of the chocolate with browned butter, brown sugar, a few drops of vanilla and, should you so desire, a pinch of ground cinnamon — it’s as flavoured as an intense chocolate cake can be. Served with whipped cream, fresh berries, and a glass of bubbly from a bottle you brought with you still in the bag from the store, it beats a generic birthday card in every way.

Method

• Preheat your oven to 180°C/fan 160°C. Line a 15cm round springform tin with a circle of parchment paper. Generously butter sides of the pan and parchment round.
• In a small saucepan, melt your butter over medium heat, stirring. After the butter melts, it will then hiss and spatter as the water cooks off, and then fragrant brown bits will form at the bottom of the saucepan. The whole process will take about three minutes.
• Remove from the heat and stir in the chocolate until melted and smooth. Cool the chocolate mixture to lukewarm, a process that can be sped up by transferring the mixture from the hot saucepan to a small bowl set in a puddle of cold or ice water. If quick-cooling like this, stir it every minute or two.
• With an electric mixer, beat egg yolks, brown sugar, and vanilla together until the mixture thickens. Slowly beat in the lukewarm chocolate mixture. The mixture will become very thick.
• Wipe clean, wash, and dry your electric beater(s), and beat egg whites and salt in a separate bowl until firm peaks form. Add a pinch of cinnamon, if desired.
• Stir one-third of the egg-white mixture into the chocolate mixture. Fold the remaining two-thirds in gently, trying to keep the batter as light as possible.
• Pour into the prepared tin, and bake for 20 to 25 minutes, or until it is puffed with a lovely dome on top (which you shouldn’t get too attached to) and a tester or skewer comes out clean or with just a couple crumbs attached.
• To serve: cool on rack for 10 minutes — it will immediately begin to sink in the middle — then run a knife around the cake to make sure it’s not stuck to the tin, and release the springform sides.
• Once it’s cool, flip out onto a plate or second rack, remove the parchment circle (if it’s stuck) from the bottom, and flip the cake back onto a small plate.
• Beat whipping cream with granulated sugar until soft peaks form. Dust the cake with icing sugar and dollop with whipped cream and berries.

Adapted from ‘The Smitten Kitchen Cookbook’

‘The Smitten Kitchen Cookbook’ is published by Square Peg at £20