Preheat oven to 200°C. Set aside a small baking dish (about 20x15cm).
Dice apples 1cm, then place in a small pot with brown sugar and 3/4 cup water. Bring to a boil on high heat. Once boiling, reduce heat to low and simmer for about 5 minutes, until apples are tender. Drain any excess water and transfer to baking dish.
Place crumble mix in a bowl and pour in melted butter. Mix together, until just combined.
Sprinkle crumble on top of apples. Bake on middle oven rack for 20-25 minutes, until crumble is golden. Reduce temperature if crumb starts to brown too quickly.
Crumble topped with cream or ice cream, if desired.