Step 1

Make Vanilla custard: Combine custard powder and sugar in saucepan over medium heat. Gradually stir in milk until smooth. Cook, stirring, for 3 to 4 minutes or until mixture boils and thickens. Remove from heat. Stir in vanilla. Cover surface with plastic wrap to prevent a skin from forming. Cool.

Step 2

Preheat oven to 180C/160C fan-forced. Grease a 7cm-deep, 20cm round cake pan. Line base and sides with baking paper.

Step 3

Using an electric mixer, beat butter, caster sugar and vanilla until light and fluffy. Add eggs, 1 at a time, beating after each addition. Sift flours over mixture. Fold until just combined. Add milk. Fold until just combined. Spoon half the mixture into prepared pan. Whisk cooled custard until smooth. Leaving a 2cm border around edge, spread custard over cake mixture. Dollop small spoonfuls of remaining cake mixture over custard. Carefully spread to completely cover custard. Smooth surface. Arrange apple slices, slightly overlapping, on top of batter. Brush with melted butter. Sprinkle with raw sugar.

Step 4

Bake for 1 hour 10 minutes or until a skewer inserted in centre comes out clean. Stand in pan for 10 minutes. Turn, top-side up, onto a wire rack. Serve warm or at room temperature, sprinkled with extra sugar.