Preheat oven to 170ºC (fan forced), with rack in the middle of the oven. Grease and line 24 cm round cake tin.
Place butter into TM bowl and mix 40 sec/50ºC/speed 4 (this will loosen up the butter, but not melt it completely which you don’t want to do … if it is completely melted the cake will be heavier).
Insert butterfly, then add yoghurt, milk, vanilla and eggs and mix 10 sec/speed 3.
Add sugar, flour and custard powder. The bowl will be very full so use the spatula to stir though some of the batter to bring liquid from the bottom to the top before continuing. Replace lid and mix 10 sec/speed 3.
Scrape around sides with spatula then mix 30 sec/speed 3.
Pour batter into cake tin smoothing the top when you have finished.
Bake for 1 hour, or when a skewer inserted into centre comes out clean.
Cool for 15 minutes before removing to a cooling rack to cool completely before icing.
This is a large cake, so perfect for birthdays and other family celebrations.