Instructions

1. Preheat oven to 180 C (350 F) standard / 160 C (320 F) fan-forced. Grease and line a 9 by 13 inch baking pan with baking or parchment paper.
2. In a large microwave-safe bowl, add butter and dark chocolate. Heat in the microwave, stirring every 20 seconds, until melted and smooth. 
3. In a separate bowl, add eggs, sugar and vanilla. Whisk together by hand for 30 seconds or so, just until creamy and combined (see photo below).
4. Add flour, cocoa powder and salt to melted butter mixture, along with the egg mixture. Stir gently using a spatula until a thick, smooth brownie batter forms. Gently stir through chocolate chips and walnuts. 
5. Pour brownie batter into prepared pan and smooth out into one even layer. Bake for approximately 35-40 minutes or until shiny on top. Brownie should no longer wobble in the middle and a toothpick inserted into the centre should come out almost clean.
6. Leave brownie in pan to cool completely. Then cut into small squares to serve. You can store brownies at room temperature or in the fridge. They also freeze really well.