Preheat an oven to 180°C and line a square brownie tray with baking paper.
In a saucepan, melt the butter and chocolate in a glass or metal bowl over a simmering pot of water. Once the chocolate has melted, turn off the heat.
Allow the chocolate to cool slightly then add in the sugar, eggs and mix well. Next add in the flour, salt, ginger and peanuts. Mix again.
Pour the mixture into a pan and flatten out. To finish, swirl the peanut butter into the top of the brownie with a knife and sprinkle over the chocolate. Bake in the oven for 10-15 minutes, you don't want to overcook it. It's better a bit fudgy.
Allow the brownie to cool and then slice in 12-16 pieces.