Step 1: Prepare the Ramekins

1. Preheat your oven to 425°F (218°C).
2. Grease the ramekins with butter and dust them with cocoa powder to prevent sticking.

Step 2: Melt the Chocolate and Butter

1. Place the chopped chocolate and butter in a heatproof bowl.
2. Melt using a double boiler (or microwave in short intervals, stirring frequently).
3. Stir until smooth and let it cool slightly.

Step 3: Mix the Eggs and Sugar

1. In a separate bowl, whisk together eggs, egg yolks, and sugar until light and fluffy.
2. Add the vanilla extract and mix well.

Step 4: Combine the Mixtures

1. Slowly pour the melted chocolate into the egg mixture, stirring constantly.
2. Gently fold in the flour and salt using a spatula. Avoid overmixing.

Step 5: Fill the Ramekins

1. Divide the batter evenly between the prepared ramekins.
2. Place them on a baking sheet for easy handling.

Step 6: Bake to Perfection

1. Bake for 10-12 minutes, or until the edges are set but the center is slightly soft.
2. Remove from the oven and let them sit for 1-2 minutes.

Step 7: Serve Immediately

1. Run a knife along the edges and carefully invert the cakes onto plates.
2. Serve with powdered sugar, berries, or vanilla ice cream.