Grind the
biscuits or muesli in food processor or blender or crush well with
rolling pin. Add apple juice to biscuit crumbs to make a spreadable
mixture. Line tart tin with aluminum foil. Press the biscuit crumb
mixture into lined tart tin. Blend yoghurt, ricotta cheese, lemon juice
and rind and apple juice in food processor or blender. Beat egg whites
stiffly. Fold them through the blended cheese mixture with the sultanas.
Pour into biscuit base. Bake approximately 30 minutes until firm. Cool
and cut into slices.