Pre-heat oven to 170 degrees celsius (fan-forced). Line a 20cm round cake tine with baking paper and set aside until needed.
Place the butter and caster sugar into the Thermomix bowl. Mix for 40 seconds, speed 3 until pale and creamy.
Scrape down the sides of the Thermomix bowl and add the remaining ingredients. Mix for 15 seconds, speed 4.
Scrape down the sides of the bowl and mix of a further 10 seconds, speed 4 to combine.
Transfer the mixture to the prepared cake tin and place into the oven. Bake for 50 - 55 minutes or until golden and cooked through when tested with a skewer.
Allow the cake to cool in the tin for 15 minutes before carefully transferring to a wire rack to cool completely.
Notes
It is essential to use butter which has been softened. If the butter is too firm, it will not incorporate with the caster sugar.If the cake is browning too much during the cooking process, cover with a sheet of foil.This cake can be baked in different sized/shaped tins, however the baking time will vary. Also please note this is a large cake, we do not recommend trying to bake it in a tin less than 20cm in diameter.Serve this Custard Cake either plain or lightly dusted with icing sugar.Store the Custard Cake in an airtight container at room temperature. Consume within five days.This cake is freezer friendly and can be frozen for up to two months.