Preheat oven to 170°C. Brush a round 22cm (base measurement) cake pan with melted butter to grease. Line the base and side with non-stick baking paper.

Use an electric beater to beat the butter, sugar and vanilla in a bowl, scraping down the side occasionally, for 8 minutes or until pale and creamy. Add the eggs, 1 at a time, beating well after each addition.

Stir in the almond meal. Add half the flour and half the milk. Use a wooden spoon to stir until well combined. Repeat with remaining flour and milk.

Arrange the apple, slightly overlapping, over the base of the prepared pan. Spoon the mixture into the pan and smooth the surface. Bake in oven for 30-35 minutes or until a skewer inserted into the centre comes out clean. Set aside in the pan for 10 minutes to cool slightly before turning onto a serving plate. Serve warm with custard.