Once melted, pour in the caramel topping and increase the heat slightly. Stir gently and make sure the mixture is well combined and reaches a hot temperature without boiling.
Pour the mixture into a large bowl. Bowl needs to be big enough for the 1.25 litres of lemonade to be poured into, with plenty of additional space as it does fizz up lots!
Pour into glasses and enjoy while warm.
If the mixture sits for a bit, make sure you give it a good stir before serving.
Recipe by Planning With Kids at https://planningwithkids.com/2013/10/06/harry-potter-food-butter-beer/