Preheat the oven to 175°C. Core the apples, score the top in a cross, then make a slit in the skin around the centre of each one with a small knife.
Combine the butter, sultanas, raisins, mixed spice and orange zest in a medium bowl. Stuff the centre of each apple with this mixture, then sprinkle with the orange juice and sugar.
Arrange the apples in a baking dish, along with 2/3 cup water. Pour 1 tablespoon brandy over each apple and bake for 45 minutes to 1 hour, until the apples are soft and the sugar is caramelised. Pour a little of the sauce over each apple and serve immediately.