Start by preheating your oven to 200°C (390°F) and generously greasing four ramekins with butter, then dusting them lightly with cocoa powder to prevent sticking.
Gently melt the dark chocolate and butter together in a double boiler or in short bursts in the microwave, stirring until smooth and glossy. Let this mixture cool slightly so it doesn't cook the eggs.
In a separate bowl, whisk the eggs, sugar, and a pinch of salt until they are light, frothy, and slightly increased in volume—this creates a silky base for your fondant.
Gently fold the cooled chocolate mixture into the eggs and sugar, using a spatula to keep the batter airy and smooth.
Sift the flour into the batter and fold gently until just combined—be careful not to overmix, as this can deflate the batter and affect the molten center.
Divide the batter evenly among the prepared ramekins, filling each about three-quarters full. Tap them gently on the counter to remove any air bubbles.
Bake in the preheated oven for 12-14 minutes, until the edges are set but the center still wobbles slightly when shaken—that's your molten magic happening inside.
Remove the ramekins from the oven and let them rest for about 30 seconds, then carefully invert each onto a plate. Gently tap or shake the ramekin to release the fondant, revealing the flowing, gooey center.
Serve immediately while warm, optionally dusted with cocoa powder or topped with berries or a scoop of ice cream for extra indulgence.
