Preheat oven to 400˚F
Generously butter and then dust with cocoa four 4-ounce ramekins. Place prepared ramekins on a baking sheet.
Chop the chocolate and butter into pieces and then melt over a double boiler, or microwave in a glass bowl in 30 second increments (stirring between increments) until melted. Stir to combine and let cool slightly then stir in vanilla extract.
Beat eggs, egg yolks, and sugar until the mixture is pale and thick, about 3 minutes. Batter should fall from the beater blades or whisk in ribbons when thick enough.
Slowly whisk the cooled chocolate and butter mixture into the egg batter and mix until combined and no streaks remain.
Add in flour and cocoa powder and blend well until combined.
Divide the batter evenly into the ramekins.
Bake in preheated oven for 11-12 minutes until firm and set on the edges but still wobbly in the center.
Let the cakes cool in the ramekins for 2 minutes and then invert onto a small serving plate or shallow bowl.
If desired, dust with a sprinkling of powdered sugar and serve warm.