BROWNIES WITH A BIT OF EVERYTHING
Preheat the oven to 180°C, 350°F, Gas 4. Line a deep 25cm x 33cm (10in x 13in) baking tray. Put the butter and the dark chocolate in a pot over a medium heat and gently melt them together, then use a whisk to incorporate them. Using an electric mixer, beat the eggs and the dark brown sugar together until they are thick and creamy, then whisk in the vanilla extract. Add the butter and dark chocolate mixture to the eggs and dark brown sugar mixture, then fold in the plain flour and the nuts. Gently mix together, ensuring there are no pockets of flour remaining. Stir in the chopped marshmallows and the crunchy peanut butter. Pour the batter into the lined baking tray and bake it for about 30 minutes. When the brownies are ready, there may still be a slight wobble in the centre; this will give them a nice gooey texture. Allow them to cool in the tin completely, before lifting them out and cutting them into squares.