Preheat the oven to 180°C

Line a 10” x 12” rectangular metal roasting tin with foil

Mix together the dry ingredients (apart from the chocolate chips) in one bowl and the wet ingredients in another

Pour the wet ingredients into the dry ingredients and mix – when they are well combined add 74g of chocolate chips

Add the crushed walnuts

Tip the mixture into the prepared tin and smooth out with a spatula.

If you had spare walnuts, you can dot them on top as decoration

Sprinkle the remaining chocolate chips over the top and bake on the middle shelf of the oven for 25 minutes (until the top has set but is very springy so that the middle is very soft).I had to cook it for longer as my oven was not cooperating. Keep testing it with a skewer to check that the middle is cooked and not runny.

Turn out onto a metal cooling rack. When cool, slice into squares and enjoy!