Place peanut butter and CARAMEL SYRUP in a small saucepan on a low heat and whisk together until it is slightly runny. Be careful not to leave it on the heat too long or it will become crumbly, you only need to warm it.
When ready, place popcorn in a large bowl, pour over peanut butter and CARAMEL SYRUP mix, then combine together using clean hands and press the mixture into the tin.