Peel, core and dice apples; place in large saucepan. Add caster sugar, cinnamon and 1/2 cup water. Simmer apples 5-8 minutes until tender.

Combine corn flour and remaining water. Stir corn flour mixture into apples until apples are syrupy.

Cut sponge cake into 2-centimeter diced pieces. Arrange 1/3 of sponge pieces in base of serving bowl. Add half of cinnamon apple pieces, including syrupy juices. Add 1 cup custard and drizzle with 1/4 cup caramel sauce. Repeat with remaining ingredients, finishing with sponge cake; chill.

Whip cream and spoon dollops over sponge cake to cover top. Garnish with apple slices, strawberry slices and caramel sauce.