Place the butter and 150g of the chocolate into a large saucepan and melt over a very gently heat.
Remove from the heat and beat in the sugar and salt.
Beat in the eggs, one by one, then sieve in the dry ingredients and stir.
Roughly chop the remaining chocolate and stir into the mix.
Pour into a 20cm (8") sq silicon mould or lined tin and bake in the centre of the oven at 180℃ (350℉, Gas 4)for about 30 minutes or until well risen, but with a slight wobble in the middle.
Allow to cool, then cut into 12 squares or 9 bars depending on how big you like your brownies.
The length of cooking time really depends on how squidgy you like your brownies. If they are too soft for your liking, they can always be returned to the oven for a bit longer.Please note: calories and other nutritional information are per serving. They're approximate and will depend on serving size and exact ingredients used.