Avocado Ice Cream

2 eggs, separated
1/3 cup granulated sugar
1 1/4 cup light cream
2 avocados
Finely-grated zest and juice of 1 large orange
1 1/4 cups heavy cream, whipped

Put egg yolks with the sugar in a bowl and beat until thick. Put the light cream in a heavy-based saucepan, and heat to just below simmering point then beat into the egg yolks. Return to the rinsed pan and cook over low heat, stirring constantly, until thickened. Set aside to cool, stirring occasionally.

Remove the flesh from the avocados and pur