Start with the mooncake dough. In a mixing bowl, combine the golden syrup, oil, and Potassium Carbonate solution together with a rubber spatula. (If using cups for measuring, make sure you get almost every last drop of syrup/oil from the measuring cups into the bowl!)
Then add the flour to the mixture, and use the spatula to combine everything into a soft dough. Do not overwork it. This step should only take 1-2 minutes. Cover the dough in an airtight container. Let it rest in the refrigerator for at least 1 hour or overnight. You should have about 470g of dough.
Make the filling:
While the dough is chilling, make the filling. In a clean, dry wok, toast the sweet rice flour for 15-20 minutes over medium low heat until it turns a light brown color. Stir often, and adjust the heat accordingly to prevent burning. Allow to cool.
Toast the pecans in a preheated oven at 300°F for 10 minutes, until fragrant. Allow to cool, and chop them—no pecan piece should be larger than a pea. Add them to a large mixing bowl, along with the brown sugar and salt. Mix well.
To the pecan mixture, stir in the melted butter, water, bourbon, oil, and vanilla. Then gradually add the toasted sweet rice flour to bind all the ingredients together. Weigh and divide the mixture into 10 equal pieces (about 60g each). Form each piece into a ball, and set aside for assembling the mooncakes.
Assemble the mooncakes:
Once the dough has finished resting, divide and weigh the dough into ten equal (47g) pieces, rolling each piece between your hands into a ball. (Weighing them will ensure each mooncake is the same size and weight.) Store the dough balls in a covered container to chill in the fridge—you’ll work with a couple at a time.
Ensure the pattern plate in your mooncake mold is locked in place, and dust the inside of the mold (the pattern plate and the sides) thoroughly with flour. Gently tap out any excess. You will repeat this process for each mooncake.
Lightly dust a work surface and a dough ball with flour, and use a floured rolling pin to roll the dough into a 4-inch/10cm circle. Use a thin, flat spatula to lift up the dough, and place it on top of a ball of filling. Gently press out the air bubbles around the filling.
Then turn the opening face-up, and carefully press the dough together to close any gaps, keeping the dough distribution as even as possible. The dough will crack easily, but it’s also easy to squish back together or patch with an extra scrap of dough. The chief goal here is to close the dough around the filling without capturing air inside. Roll between your hands to create a smooth ball.
Lightly dust the assembled ball with additional flour. Place it on a lightly floured work surface, then press the mooncake mold onto the ball until the base of the mold makes contact with the work surface. Firmly press down on the spring until you feel resistance. Lift the mold and gently press the mooncake out of the mold. If any dough gets stuck in the mold or you have areas where the filling is peeking through the dough, get a small piece of the scrap/mending dough to patch up the area. Then clean the mold (a toothpick helps get dough out of any nooks and crannies in the mold) and dust it more thoroughly with flour. Then gently press in on all sides of the mooncake to make it smaller, so it can go back in the mold for reshaping.
Place the mooncakes on a baking sheet about 1 inch (2.5cm) apart as you make them. Repeat until you’ve assembled all the mooncakes. (Note that they will not change size during baking.)
Bake the mooncakes:
Preheat the oven to 325°F/160°C when you’re almost finished assembling the mooncakes. Right before baking, dip your fingers into a bowl of water, and fling the water on your fingers onto the mooncakes a few times. This gently misting prevents the dough from cracking.
Immediately put the mooncakes in the oven and bake for 5 minutes. (Remember to set the timer!) Now prepare the egg wash by whisking the egg yolk and 3 tablespoons of water together.
After the mooncakes have been baking for 5 minutes, take them out of the oven and immediately lower the oven temperature to 300°F/150°C. Very lightly brush each mooncake with egg wash (preferably using a natural bristle pastry brush), being careful not to allow any egg wash pool in the nooks and crannies of the mooncakes. Put them back in the oven, and bake for another 15-17 mins, until the mooncakes are a light golden brown.
Video
Notes
When the mooncakes first come out of the oven, the dough will look a bit dry, and not oily like what you are used to when opening packaged mooncakes. This is normal. Cool completely, and then store the cooled mooncakes in an airtight container for 1-2 days, and the outside will get that nice shiny sheen you recognize! Store your mooncakes in an airtight container in the refrigerator for up to 10 days, and enjoy.Mooncakes are a calorie dense treat. They were made for sharing! :)