Prepare your ramekins: Brush the inside of each ramekin generously with softened butter, making sure you get right up to the rim. Place a teaspoon of cocoa powder into one ramekin and tap it around until the entire buttered surface is coated. Tip the excess into the next ramekin and repeat. You should see a fine, even brown coating with no bare spots. Place the ramekins on a baking tray and set aside.

Melt the chocolate and butter: Fill a small saucepan with about 3cm of water and bring it to a gentle simmer. Place your heatproof bowl over the pan — the bottom should not touch the water. Add the butter and dark chocolate pieces. Stir occasionally with a spatula until everything is smooth, glossy, and fully liquid. The smell will be intensely chocolatey. Remove the bowl from the heat and let it cool for five minutes. You want it warm, not hot, so it does not scramble the eggs later.

Whisk the eggs and sugar: In the bowl of your stand mixer (or a large mixing bowl if using a hand mixer), combine the whole eggs, egg yolks, and caster sugar. Whisk on high speed for about 4 minutes. You are looking for a thick, pale mixture that leaves a ribbon-like trail on the surface when you lift the whisk. The texture should be airy and noticeably increased in volume.

Fold in the chocolate mixture: Pour the cooled melted chocolate and butter into the egg mixture. Add the vanilla extract and salt. Using a rubber spatula, fold gently from the bottom up. Do not stir vigorously — you want to keep as much air in the batter as possible. Stop folding when you can no longer see any streaks of chocolate. The batter will be thick, dark, and velvety.

Add the flour: Sift the plain flour directly over the batter. Fold it in with the same gentle motion, just until the flour disappears. Over-mixing at this stage will make the cakes tough. The final batter should be smooth, thick, and fall from the spatula in a slow, heavy ribbon.

Fill the ramekins: Divide the batter evenly among the four prepared ramekins. Each should be about three-quarters full. Tap each ramekin gently on the work surface to level the batter. At this point, you can cover them with cling film and refrigerate for up to 24 hours, or bake immediately.

Bake to perfection: Preheat your oven to 200°C (180°C fan) / 400°F / Gas Mark 6. Place the baking tray with the ramekins on the middle shelf. Bake for exactly 12 minutes. The cakes should look set around the edges but the centre will jiggle slightly when you gently shake the tray. The tops will be puffed and have a slight dome. You will see a thin, dry crust form on top — this is the sign they are ready.

Rest and unmould: Remove the tray from the oven and let the ramekins sit on a wire cooling rack for exactly 60 seconds — no longer. Run a small, sharp knife around the inside edge of each ramekin to loosen the cake. Place a serving plate upside down over the ramekin, then flip it over in one confident motion. Lift the ramekin away carefully. You should see a perfectly shaped, domed cake with a dusting of cocoa powder on its surface.

Finish and serve immediately: Dust each cake with icing sugar through a fine-mesh sieve. Add a small dollop of double cream or a scoop of vanilla ice cream on the side. Garnish with two or three fresh raspberries or a sliced strawberry. Serve within 2 minutes — the lava waits for no one.