1. Heat the oven to 190C/375F/Gas 5. Line a 20x30cm/8x12in roasting tin with baking parchment.
2. Gently melt the butter and the sugar together in a large pan.
3. Take off the heat and beat in the rest of the ingredients.
4. Turn into the roasting tin and bake for 30-40 minutes until the top of the brownie is firm but the inside still feels soft.
5. Take out of the oven and cool in the tin. Cut into 5cm/2in squares when cool.
suggestion- for an extra twist add marshmallows in step 3!