Quarter, peel and core the apples. Put into a pan with the apple juice, bring to the boil, cover and cook for 2 - 3 minutes. Remove from the heat and leave to cool. Wash the basil, shake dry and pick off the leaves.
Puree the apples with the cooking liquid, lemon juice, basil leaves, 1 tbsp pistachios, and sugar. Blend in the grated lemon rind, cream, and ricotta. Finely chop the rest of the pistachios and mix in.
Transfer the mixture to a metal bowl and put into the freezer for about 4 hours. Stir frequently to prevent any large ice crystals from forming (alternatively finish off in an ice cream maker).