Butter the inside of 4 (5 1/2 ounce) ramekins. Place them in a casserole dish. (or a 9x9 pan - makes them easier to move and you will need it later)
Whisk together (I use a blender) egg yolks, eggs, and sugar in a bowl until light, foamy, and lemon colored.
Melt chocolate and butter in a microwave-safe bowl in 30-second intervals, stirring after each melting, 1 to 3 minutes.
Add melted chocolate mixture into egg and sugar mixture (stir).
Add cocoa powder into the mixture (stir).
Add flour and salt into the mixture (stir).
Add vanilla extract into the batter.
Divide batter evenly between the ramekins
Refrigerate 30 minutes.
Preheat an oven to 425 degrees F (220 degrees C).
Arrange the ramekins in a casserole dish. Pour enough tap water into the casserole dish (around the outside of the ramekins) to reach halfway up the sides of the ramekins.
Bake in the preheated over for 15-18 minutes. Set aside to cool for 15 minutes.
Loosen the edges from the ramekin with a knife.
Save with Ice Cream!