To prepare filling: Steam salted egg yolks over high heat until cooked, about 10 minutes. Set aside to cool. In a mixing bowl, crush the egg yolks until powdery. (1)Add in the milk powder, custard powder and sugar. (2)Mix well. (3)Add in the butter and (4)evaporated milk and (5)mix thoroughly. Cover the bowl with clingwrap and store in the freezer until needed.
To prepare dough: In a large bowl, mix Hong Kong flour, yeast, sugar and carrot juice. Add in the shortening and mix well. Knead the dough on a flat, lightly-floured surface until smooth. Portion the dough out into small balls of 30g each.
To assemble: (1)Roll out into circular shapes with a thickness of roughly 2mm. (2)Top each circle with a spoonful of filling. (3)Gather the edges and (4)fold over, (5)pinching to seal the pau.
(6)Place in scalloped moulds and allow the pau to rest for an hour to proof. Steam over high heat for 5 minutes. Serve hot.