Custard: Serve cake warm with custard. Cake can be made up to two days ahead. Keep in an airtight container.
• 200g unsalted butter, chopped, at room temperature
• ¾ cup brown sugar, firmly packed
• 2 tsps vanilla bean paste
• 2 tsps finely grated lemon rind
• 3 free-range eggs, at room temperature
• ⅓ cup milk
• 1⅔ cups self-raising flour
• 1 tsp ground cinnamon
• 50g unsalted butter, melted
• ½ cup brown sugar, firmly packed
• 2 large Granny Smith apples (160g each), peeled, cored
Grease a 22cm round cake pan. Line base and side with baking paper, extending paper 2cm above pan edge.
Beat butter, sugar, vanilla and lemon rind in a small bowl of an electric mixer until fluffy. Beat in eggs, one at a time, until combined. Transfer to a large bowl.
Stir in milk, then combined sifted flour and cinnamon, in two batches, until combined.
To make apple topping, pour butter over base of pan. Sprinkle with sugar. Thinly slice apples. Arrange slices over sugar in base of the pan in a single layer, slightly overlapping.
Spoon the cake mixture over the apples. Smooth top.
Cook in a moderately slow oven (160°C) for about 50 to 55 minutes, or until a skewer inserted into the centre comes out clean. Stand in pan for 20 minutes. Invert onto a serving plate. Cool to room temperature.
Serve cake with double cream, if desired.