Steps
Preheat your oven to 425°F (220°C).
Grease a ramekin with butter and dust with cocoa powder, tapping out excess.
In a microwave-safe bowl, combine dark chocolate and butter. Microwave in 30-second intervals, stirring until smooth.
In another bowl, whisk together the egg and sugar until well combined.
Gradually mix the melted chocolate into the egg mixture.
Fold in the flour and salt until just combined.
Pour the batter into the prepared ramekin.
Bake for 12-14 minutes until the edges are firm but the center is still soft.
Let it sit for 1 minute before inverting onto a plate. Enjoy warm, optionally with ice cream or berries!