Spray a 20x20cm pan with non-stick spray or line the pan with greaseproof paper.
Place the butter and chocolate in a glass bowl over a pot of simmering water (making sure the bowl does not touch the water).
Stir until the chocolate and butter have fully melted.
Beat the eggs with a fork and quickly beat into the chocolate mixture.
Mix the flour and cocoa powder and gently fold it into the chocolate mixture.
Pour into the prepared pan and spread out evenly. Heat the peanut butter in the microwave for 15 seconds just to make it softer and easier to spread.
Spread the peanut butter over the chocolate mixture and with a toothpick make swirls so that the peanut butter and chocolate shows a marbled effect.
Bake for 35 minutes.
Remove from the oven and cool completely before cutting it into blocks.
Reprinted with permission of My Easy Cooking.
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