Preheat your oven to 425°F (220°C). Grease the ramekins with butter and lightly dust with cocoa powder, tapping out the excess. This will help the cakes release easily.

In a double boiler, melt the chopped chocolate and butter over low heat, stirring occasionally until smooth. You can also use a microwave-safe bowl and heat the mixture in 20-second intervals, stirring between each session.

In a separate bowl, whisk together the eggs, egg yolks, and powdered sugar until the mixture becomes light and slightly frothy.

Slowly pour the melted chocolate and butter into the egg mixture, whisking constantly to avoid curdling the eggs. Add the vanilla extract and salt, and mix until well combined.

Gently fold in the flour using a spatula until the batter is smooth. Be careful not to overmix, as this can make the cakes dense.

Divide the batter evenly among the prepared ramekins. Place them on a baking sheet to ensure even baking and easy handling.

Bake for 12–14 minutes, or until the edges of the cakes are firm but the center is still soft and slightly jiggly. The top should appear set, but when you insert a spoon or fork, the middle will be gooey.

Let the cakes cool in their ramekins for about 1 minute before gently running a knife around the edges. Carefully invert each cake onto a serving plate. Serve warm with a dusting of powdered sugar, a scoop of vanilla ice cream, or fresh berries.