Peanut Butter Fudge

I want to make something sweet and naughty for Bon Fire Night. So I found in my recipe file a recipe for fudge by Sophie Dahl and decided I will make it and see if I can avoid setting my kitchen alight.

Ingredients
125g butter
500gdark brown sugar
120ml milk
250g crunchy peanut butter
1 vanilla pod, seeds only
300g icing sugar

Melt the butter in a saucepan over a medium heat. Stir in the brown sugar and milk, and bring to the boil for 2-3 minutes, without stirring.
Remove from the heat, and stir in the peanut butter and vanilla seeds.
Add the icing sugar in a large bowl, and pour the hot butter and
sugar mixture on top. Using a wooden spoon, beat the mixture until
smooth.
5. Pour into a 20cm/8in square baking tray, and set aside to cool
slightly, then place in the fridge to chill completely.
6. Cut the fudge into squares with a sharp knife, turn out of the tin and
store in an airtight container.