Preheat oven to 180°c

Line a 25 cm square baking tin with greaseproof paper

In a large bowl over simmering water, melt butter and chocolate until smooth. Add nuts in if desired and set aside to cool

In a separate bowl, mix together cocoa powder, flour, baking powder and sugar.

Beat 4 eggs and add into cooled chocolate+buyer mixture

Mix in dry ingredients until well combined, taking care not to over mix

Poor brownie mixture into baking tray place or into the oven for ~25 minutes

Check every 5-10 minutes after the 25 minute mark to see if brownie is cooked. Top should be firm to the tap and the skewer should be most at the tip

Allow to cool in the tray before transferring to a chopping board to cut into chunky squares.

Serve with ice cream