Melt the chocolate and butter in a bowl over a saucepan of simmering water. Be careful the bowl doesn’t get too hot by removing from the heat if necessary. Once melted leave to cool a little.
Beat the eggs with an electric whisk for about 6 minutes adding the sugar a little at a time. The egg and sugar mixture should become frothy.
Slowly pour in the melted chocolate and butter mixture so it all becomes emulsified. Then add the rye, baking powder and fine sea salt and mix until it all combines.
Weigh out the mixture into a lined baking tray.
Sprinkle with the cocoa nibs.
Place in the oven for 30 minutes until the brownies puff up, but are still wobbly.