Preheat the oven to 375 oF / 190 oC. Place the quartered apples in an ovenproof dish, add lemon juice and grated rind, and sprinkle the sugar over the apples. Cover the apples with buttered greaseproof paper. Bake until the apples soften but before they begin to break up (about 35 minutes). Turn the oven down to 275 oF/140 oC. Add the quartered pears to the dish with the apples. Add the lemon rind and juice, and spice. Mix together gently. Slice the cake, and butter generously. Cut into cubes and cover the fruit with the cake, butter side up. Brown slightly under the grill. Whisk the egg whites until they begin to stiffen. Continue whisking, adding the caster sugar approximately 1 tb at a time, until you have about half the sugar left. Fold in the remainder and pile on to the fruit and cake, peaking the meringue with a fork. Bake in the oven for about 25 minutes or until the meringue has set. Serve hot or cold with pouring cream.