1. Place dates, sugar, vanilla and ½ cup water in a small saucepan. Stir on medium heat until mixture boils. Remove from heat and stir in baking powder. Set aside to cool.
2. Preheat oven to 180C or 160C fan. Grease and line an 18cm square cake pan.
3. Arrange half of apple over base of prepared pan. Stir apple puree and eggs through cooled date mixture until combined. Stir in flour. Pour into pan, taking care not to disturb apples. Smooth top with a spatula and arrange remaining apples on top. Bake for 40-45 minutes, until a skewer inserted comes out clean.
4. Cool in pan for 5 minutes before turning out onto a serving plate, baked apples side up. Serve pudding drizzled with custard if you like.