Preheat and prepare: Set your oven to 200°C (180°C fan). Butter the insides of four 150ml ramekins thoroughly, then dust with cocoa powder, tapping out any excess. This coating creates a dark, non-stick crust that helps the cakes release cleanly.

Melt the chocolate and butter: Place the chopped chocolate and cubed butter in a heatproof bowl over a pan of barely simmering water. Stir gently until smooth and glossy — you will see the mixture turn from lumpy to a silky, dark river. Remove from heat and let it cool for two minutes.

Whisk the eggs and sugar: In a separate large bowl, whisk the whole eggs, egg yolks, caster sugar, and vanilla extract together. Whisk vigorously for about 2 minutes until the mixture becomes pale, thick, and leaves a ribbon trail on the surface when you lift the whisk.

Combine the mixtures: Pour the melted chocolate mixture into the egg mixture. Fold gently with a spatula, scraping the bottom of the bowl, until you see a uniform, dark brown batter with no streaks of egg. The batter will look thick and fudgy at this stage.

Add the dry ingredients: Sift the flour and salt over the batter. Fold again with the spatula, just until the flour disappears. Do not overmix — stop as soon as you cannot see any white flour. The batter should be smooth, thick, and smell intensely of chocolate.

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 worktop to settle the batter.

Bake: Place the ramekins on a baking tray and bake for exactly 12-14 minutes. The cakes are ready when the tops look set, the edges are firm, and the centre jiggles slightly when you gently shake the tray. You will smell a rich, baked chocolate aroma filling your kitchen.

Rest and serve: Let the ramekins cool on a wire rack for exactly 1 minute. Run a small knife around the inside edge of each ramekin, place a plate on top, and invert. Lift the ramekin off gently — you should see a perfectly formed cake with a glossy, molten centre spilling out.