Combine caster sugar, water, orange blossom water and orange zest in a saucepan over a medium heat.

Stir for 2 minutes or until the sugar has dissolved and bring to the boil. Reduce heat and allow to simmer for 2 minutes.

Remove saucepan from heat and cool to room temperature.

Place yoghurt into a medium sized bowl and using a fine mesh sieve strain the syrup into the bowl. Combine with a wooden spoon.

Roughly chop the blueberries and fold into the yoghurt mixture. Using a small ladel, fill your moulds with the mix and place into the freezer for 5 hours or overnight. Serve.