In a bowl, mix flour, baking powder, baking soda, Ovaltine, to combine
In a separate bowl, beat eggs, ovalet, and sugar for 8 minutes, until pale and fluffy
Stir in dry ingredients, followed with essence and melted butter, pour into a loaf pan
Preheat steamer, and steam cake for 10 minutes
Cool cake before applying custard
In a bowl, mix custard powder, milk, and sugar, microwave per container instruction (6 minutes)
Take out from the bowl, stir in chocolate pieces to melt completely. Cool to almost rook temperature, it will be spread consistency
Spread custard on cake and chill overnight
Slice and serve!