In a microwave-safe bowl, melt the chocolate and butter in 20-30 second increments, stirring until smooth. (Alternatively, use a double boiler.) Allow the mixture to cool slightly to prevent the eggs from scrambling when added.

In a medium mixing bowl, whisk the eggs, egg yolks, sugar, and salt until light and frothy, about 2-3 minutes. Use a hand whisk or an electric mixer on low speed.

Gently fold the cooled chocolate mixture into the egg mixture. Sift the flour into the batter and add the vanilla extract. Mix until just combined. Do not over-mix.

Divide the batter evenly among the prepared ramekins, filling each about 3/4 full.

Place the ramekins on a baking sheet and bake for 10 to 12 minutes. The edges should be set, but the centers will remain soft. Do not over-bake. (If unsure, gently tap the ramekin—if the edges are firm but the center jiggles slightly, it’s ready.)

Allow the cakes to rest for 1 minute. Gently run a knife around the edges to loosen and carefully invert each ramekin onto a serving plate. Dust with confectioners' sugar and serve immediately with your favorite toppings.