Heat your oven to 425°F before you start. Grease and flour your six ramekins well.
Melt the Chocolate
Place the chopped chocolate and butter in a bowl. Microwave in 30-second bursts until smooth.
Beat the Eggs
In the large bowl, beat the whole eggs, yolks, sugar, and salt for 5 minutes.
Watch for Volume
The egg mix should be very thick and pale yellow. This adds a light air to the cake.
Fold the Chocolate
Slowly pour the warm melted chocolate and vanilla into the egg mixture. Fold gently.
Add the Flour
Sift the flour over the batter. Stir very lightly until you see no more white streaks.
Fill the Ramekins
Divide the batter evenly among the prepared dishes. Place them on a baking sheet.
Bake to Perfection
Bake for 8 to 10 minutes. The sides should be firm, but the center must still jiggle.
Notes
Use good chocolate. Since there are few ingredients, the quality of the chocolate defines the taste.Don't overbake. Even one extra minute can turn the molten center into a solid sponge cake.Butter the dishes. Generously grease the ramekins and dust with cocoa powder for an easy release.Room temp eggs. Warm eggs whip up much higher and create a more delicate cake structure.Invert carefully. Let the cakes sit for one minute, then flip them onto a plate with a towel.Serve immediately. The "lava" effect only lasts while the cake is hot from the oven.