Pre-heat your oven to 170ºC/150ºC fan. Line a 20x30cm baking tray with greaseproof paper.

Melt your butter (200g) and milk chocolate (200g). I prefer to melt mine in a saucepan over a very low heat, stirring constantly to ensure that it doesn’t burn and the butter and chocolate combine. Alternatively you can also melt them in the microwave (about 1½-2 minutes) or using a bain marie. Once your butter and chocolate have melted pour them into a different bowl to cool. They must be fully cooled before they are added to the other ingredients.

Add the chocolate and butter mixture (it must be cooled!) and fold it into the egg mixture taking care not to knock out the air.

Sift your self-raising flour (100g) and cocoa powder (30g) into the mixture and fold everything together. Stop folding as soon as they are combined to avoid overmixing.

Pour the mixture into your prepared tin, then use a teaspoon to put blobs of peanut butter onto the top of your brownie mixture. Use a knife or skewer to swirl it into the brownie mixture.

Break your Oreos (9 Oreos) into pieces (about 3 each) and scatter them over the top (if you want to make your brownies easier to cut try and put them in the middle of where you think each brownie will be).

Cook for 30-35 minutes until the edges of the brownie are just starting to come away from the sides of the tin.

Remove your brownies from the oven and leave to cool in the tin. Once cool remove them from the tin and cut them into 12 pieces (or 48 pieces if you’re making mini brownies). You can trim the edges if you want them a bit neater.