Cut avocados in halves lengthways, remove seeds and reserve. Scoop pulp from shells and mash smoothly with a fork. Add Sugar to taste and stir in the cream. Put into serving bowl, return seeds to the pulp, cover closely with plastic wrap and chill before serving.The presence of the seeds in the purée is said to keep the avocado from discolouring, but make sure that the surface is protected from air by putting the plastic on the surface of the mixture.
If you like, extra whipped and sweetened cream can be piped over the top of the dessert and a few paper.thin slices of avocado (sliced at the last moment and sprinkled with lemon juice) used for decoration. Note: While some favour rum for flavouring, I prefer to let the delicate avocado flavour stand alone.