Step 1

Combine cornstarch, custard powder, and half of the sugar together in a large bowl.

Step 2

Combine remaining sugar and milk in a medium saucepan and heat over medium-low heat until sugar is dissolved, stirring occasionally to prevent scorching. Don't let milk come to a boil.

Step 3

Add egg yolks to cornstarch mixture and whisk together to form a thick, smooth paste.

Step 4

Add in the warm milk a third at a time, whisking vigorously so that eggs don't cook.

Step 5

Once the milk is incorporated, pour the mixture back into the saucepan and cook over medium heat, stirring constantly with a wooden spoon.

Step 6

Cook for about 5 minutes, stirring constantly to prevent scorching, until mixture thickens and comes together. This will happen quickly, so don't leave the stove and don't stop stirring once it starts to thicken.

Step 7

Once the mixture thickens, remove immediately from heat and add in butter. Stir until butter melts and is incorporated.

Step 8

Turn out mixture into a bowl and press a piece of plastic wrap over the surface. Place in refrigerator and chill for at least 30 minutes until mixture is cool and has solidified enough to scoop.

Step 9

Combine the glutinous rice flour, rice flour, wheat starch, and confectioner's sugar in a large bowl and whisk to together to combine.

Step 10

Combine the milk and vegetable oil together in a bowl. Pour into the flour mixture and stir to combine.

Step 11

Strain the mixture into a clean heatproof bowl and let sit for 30 minutes. It will thicken slightly.

Step 12

Place bowl on a steamer rack in a steamer, or you can improvise a steamer with a large lidded saucepan partially filled with boiling water.

Step 13

Steam for about 25-30 minutes until the mixture is solid, has turned slightly translucent, and a knife inserted into the mixture comes out nearly clean (a few drops of liquid is ok).

Step 14

Remove from steamer and let sit on a towel or rack for a few moments to cool.

Step 15

Scoop the dough out onto a clean surface lined with plastic wrap (it is very important to use plastic wrap - the dough will stick to any other surface. Do not use try to use another surface like marble dusted with flour).

Step 16

Cover the dough with another piece of plastic wrap and knead for several minutes until the dough is very soft and has an oily sheen. This is very important so the dough stays soft and workable later. Also it's important to use the plastic wrap on top of the dough as again if you use bare hands the dough will stick to your hands.

Step 17

Wrap the dough in plastic wrap and chill for about 3 hours until fully cool. You can also chill it overnight but it may be a little stiffer when first removed from the refrigerator.

Step 18

Put the glutinous rice flour in a large frying pan and cook on medium heat, stirring with a wooden spoon, until it starts to turn golden brown and smells fragrant. Remove and let cool.

Step 19

Take the filling out of the refrigerator. Scoop out 25g portions and roll into balls. It's ok if they aren't completely smooth. Place on a plate lined with plastic wrap and place back in the refrigerator.

Step 20

Cover your worksurface with plastic wrap.

Step 21

Take the dough out of the refrigerator. Cut off 25 portions and roll into balls. Place on a plate lined with plastic wrap. If they get too soft and sticky at any time, you can put them back in the refrigerator for a few minutes to firm up.

Step 22

Dust a 50g mooncake mold lightly with toasted glutinous rice flour, or cornstarch.

Step 23

Take a piece of dough and roll it out on the plastic wrap with another sheet of plastic wrap on top, into a round disc. Don't make it too thin.

Step 24

Place a ball of filling in the center and wrap the dough around it. Roll it lightly between your palms to seal the dough and ensure it's evenly wrapped around the filling.

Step 25

Fit the mooncake seam side down into the mold and press in gently. Place the mold on the work surface and holding it in place, press down firmly to stamp the top.

Step 26

Gently press the mooncake out of the mold.

Step 27

Place in an airtight container lined with plastic wrap and refrigerate for a few hours. Snow skin mooncakes are typically served cold - if they seem really firm, you can let them sit for 10-15 minutes at room temperature first. They will keep for a couple weeks but are best eaten within a few days of making them.