01 - Preheat oven to 425°F. Grease four 6-ounce ramekins with butter and lightly dust with cocoa powder or flour.
02 - Combine butter and chopped chocolate in a heatproof bowl. Melt over a double boiler or in the microwave in 30-second intervals, stirring until smooth.
03 - In a separate bowl, whisk together eggs, egg yolks, granulated sugar, and salt until the mixture is light and slightly thickened.
04 - Gently fold the melted chocolate mixture into the egg mixture. Sift in flour and fold just until evenly incorporated.
05 - Evenly divide the batter among the prepared ramekins. Set ramekins on a baking sheet.
06 - Bake for 11 to 13 minutes until the edges are set and the centers remain soft. Avoid overbaking to retain a molten center.
07 - Let cakes rest for 1 minute. Carefully invert each ramekin onto a plate.
08 - Serve immediately, garnished with powdered sugar, berries, ice cream, or whipped cream as desired.