Rum and pineapple are a great classic combination. I like to grill the pineapple on the barbecue beforehand as it emphasizes the sweetness of the fruit. Frozen yoghurts don't require as much work as custard base yoghurts as its just a matter of adding it to the fruit puree and then churning in the machine. When making ice creams with alcohol you do need to be careful with the amount you put in, too much and it won't freeze properly as alcohol impacts the freezing point. Ensure you use full fat yoghurt as a lighter one will not give you a good creamy mouthfeel. 

600g fresh pineapple, core and skin removed and sliced into 2cm thick rounds

150g full fat Greek yoghurt

30ml lime sugar syrup

50g light brown sugar

80ml dark rum (I used Black Tot rum for this recipe)

1g maldon sea salt

Set your barbecue up for direct cooking at 200c

Quickly grill the slices of pineapple until you have a nice slight char on each side

Place to one side and allow to cool

Once cool, whizz in a food processor with the sugar, syrup and rum until you have a puree

Add the yoghurt and sea salt and pulse until it is well combined

Place the yoghurt mix in the fridge for 4 hours to allow to cool

Set up your ice cream machine and place the freezer on for 10 minutes

Turn on the churner and pour in the yoghurt mix

You can either serve immediately when finished or it will keep in the freezer for up to one month