Freeze the 2 Bags of Pineapple Lumps overnight or until hardLine a slice tin (or 25cm square cake tin) with baking paper or spray well with cooking spray and set aside.Crush the biscuits in a food processor, you can also pulse the pineapple lumps in here as well but I prefer to chop them by hand for bigger chunks - but this way quicker!Cut Pineapple Lumps into small pieces (you can reserve half a cup for the topping if you desire)Melt the butter and condensed milk in a large saucepan on low heat until melted and mixed together well, alternatively do this step in the microwave.Pour the pineapple lumps & biscuits mixture into the butter/condensed milk mixture and combine wellSpoon the biscuit mixture into the slice tray and press down very firmly using the back of a large spoon until tightly packed and smooth.Melt your chocolate in the microwave with 10-20 second bursts, stiring in between until completely melted or you can use a double boiler.Pour the chocolate onto the slice and using the back of a spoon spread chocolate evenly over the slice.If you reserved some pineapple lumps sprinkle these over the top of the slicePlace in the fridge for at least two hours (preferably overnight).Take the slice out of the fridge and leave for 20 minutes before slicing (this way your chocolate will be less likely to crack).Cut the slice into squares.This slice will keep in an airtight container in the fridge for 5 days (but lets face it – it won’t last that long anyway!)