Defrost the blackberries in a sieve over a large bowl

Once defrosted place the blackberries with 60mls of the juice into a food processor

Blend until smooth

Pass through a sieve into the bowl with the juice left over from defrosting

Discard the solids

Place in the fridge overnight

Mix in the simple syrup and place into your ice cream churner

Churn for 7 minutes before adding the liqueur

Churn for a further 5 minutes

Place into a freezer container and freeze for at least 2 hours before serving