Whisk the eggs and sugar until light and fluffy and tripled in size.
Heat chocolate, salt, and butter in a bowl over a pan of simmering water until melted and glossy.
Remove chocolate mixture from heat and allow to cool for a few minutes.
Fold chocolate mixture into the egg mixture.
Grease a pie tin well and fill with brownie mixture.
Tap the tin on work-surface a few times to remove any air bubbles.
Place the tin in a roasting tray that is filled halfway with boiling water.
Place the roasting tray in the oven and bake for 40 minutes at 120ºC or until set with a slight wobble.
Remove from oven and leave to cool in the water-filled roasting tray for 1 hour.
Serve with cream or ice-cream and enjoy!