I made some modification as the original recipe seems 'too heavy' to me.
220g unsalted butter
100g castor sugar
70g brown sugar
2tsp vanilla extract
150g plain flour - sieved
100g cocoa powder
1/2 tsp baking soda
1 bar 70% dark chocolate - chopped and spilt equally into 2 portions.
30g almond nut - chopped
*Lined the base and sides of the 8" square tin or 7" X 13" rectangular tin.
*Preheat oven at 180C.
1. Cream butter, castor sugar, brown sugar and vanilla extract until well combined.
2. Sieve in all dry ingredients (except the chocolate and nuts) into a mixing bowl.
3. Add in the sieved ingredients in small portion (i added 1 tbsp at a time) to the butter mixture and cream till well combined. *Note: the batter will turn out really really thick, almost like a soft dough!
4. Add 1 portion of the chopped chocolate and nuts to the mixture. You can use the back of the spatula to mix in.
5. Spread the batter to the baking tin and sprinkle the last portion on the chopped chocolates over it, pressing it lightly down to the batter.
6. Send to bake for 30min.