Finely slice the mandarins and remove any pips

Place the pips into a piece of muslin and tie together with cooking string.

Place the mandarins and pips into a large bowl and cover with water. Leave to stand overnight.

The next day, pour the mandarins, pips and water into a large pan and bring to the boil.

Reduce to simmer and cook for 30 minutes.

Remove from heat and remove the muslin bag with the pips and discard.

Measure the fruit mixture into a pan and then add one cup of sugar for each cup of fruit mixture.

Return pan to heat and stir until the sugar dissolves.

Bring to the boil and boil uncovered for approximately 30 minutes or until the mixture reaches setting point. (To test for setting point, place a spoon of mixture onto a chilled saucer and put into the fridge for a few minutes to cool. Then run your finger through the mix and if it stays separated, it is ready.)

Stir in the Cointreau, remove any scum from the top of the mixture and then pour into warm sterilized jars and seal with lids immediately.