01 - Preheat the oven to 425°F. Grease four 6-ounce ramekins with butter and lightly dust with flour, tapping out excess.
02 - Gently melt the chocolate and butter together in a heatproof bowl over simmering water or in the microwave, stirring until smooth. Remove and set aside to cool slightly.
03 - Whisk the eggs, egg yolks, and sugar together in a separate bowl until pale and slightly thickened, approximately 2 minutes.
04 - Fold the melted chocolate mixture into the egg mixture until fully combined.
05 - Sift the flour and salt into the batter and gently fold until just incorporated.
06 - Evenly divide the batter among the prepared ramekins.
07 - Arrange ramekins on a baking tray and bake for 10 to 12 minutes until the edges are set but the centers remain soft and slightly jiggly.
08 - Remove from oven and allow to rest for 1 minute. Run a knife around edges, then invert each cake onto a serving plate.
09 - Dust with cocoa powder or powdered sugar if desired. Serve immediately with a scoop of vanilla ice cream and garnish with fresh berries or mint.