To make the filo baskets, take 4 sheets of filo pastry and spray well with cooking spray. Layer on top of one another and cut 4 even strips lengthways then cut in half crossways, making 8 squares to push into greased muffin pans. Repeat with remaining 4 sheets of pastry.
Cook at 180°C/350°F for 8 minutes until golden and crisp. Remove carefully onto wire racks to cool.
To make the carrot filling, melt butter in a deep saucepan, add carrots and spring onions and cook for 4-5 minutes. Add water and salt and simmer covered for 5 minutes. Remove from heat, stir in flour, cook for 1 minute. Remove from heat, stir in cream and port. Return to heat and cook on medium-high until thickened.
Set aside to cool then spoon into filo baskets. Freeze.
Thaw completely before reheating and warm at 160°C/300°F for 15 minutes.
Take care when packing for the freezer as the points of the baskets will be quite delicate. Will freeze for up to a month.