Add sago into boiling water (do no need to wash the sago) , cook under medium heat for 10 minutes, you will see there are some white spots. Remove from heat, cover the lid for 15 minutes. Sago will become transparent, rinse it under water, then drain well. 

In a bowl, mix custard powder and half of the milk together, then add in eggs, mix well. 

Add another half of the milk in a pot, together with evaporated milk, butter and sugar. Cook under medium heat but do not boil it. Then gradually add in custard mixture, keep stirring. Cook at medium heat and after few minutes, the mixture will become thicken, remove from heat. Then add in sago, mix well. 

Add the mixture into ramekins, then place in a baking tray and pour hot water into the tray (about 1/3 high) . Pop in preheated 200C oven and bake for 20-25 minutes or until the surface is slightly caramelised.