Directions

Make the lava Filling (7g each, makes 16 fillings)

1. Bake the salted egg yolks in a 360°F / 182°C oven for 12 minutes. The runny lava center and the middle custard layer need two salted egg yolks each, so bake four all at once. You can buy salted egg yolks from the Asian market. If you don't have access to buy them, you can check this video to learn how to make your own.
   
2. Meanwhile, combine the unsalted butter, whipping cream, gelatin powder, sugar, milk powder, and American cheese in a saucepan. Although cheese is not a traditional Chinese ingredient, nowadays, mooncake has developed many new fillings with all kinds of flavors and using cheese is pretty popular.
   
3. Remove the salted egg yolk from the oven. Reserve 2 on the side and press the other 2 through a fine sieve into the saucepan. Once done, make sure you scrape the bottom of the sieve so you don't waste anything.
   
4. Put a piping tip into a piping bag. Twist the tip, then place the bag into a cup. Set it aside.
   
5. Put the saucepan over a low-heat stove and stir for a few minutes or until the butter and cheese are melted.
   
6. Turn off the heat and pour the mixture into the piping bag. Note: this mixture is fluent, so please hold the opening carefully.
   
7. Evenly squeeze the mixture into silicone molds. This recipe makes 16 mooncakes; each filling should be about 7g. Please use a scale, to be precise. By the way, if you don't have round silicone molds, the square one will also work; you just need to round the corners before wrapping.
   
8. Place the lava filling in the freezer overnight.
   

Make the Milk Yolk Custard Filling (18g each, makes 16 fillings)

1. In a mixing bowl, combine the egg yolks, sugar, milk, and melted butter. Make sure the milk is warm; otherwise, the butter will clump up. The milk yolk custard filling requires three egg yolks; if you don't know what to do with the egg whites, use one whole egg instead.
   
2. Sieve in the cake flour and milk powder, then stir until no lumps.
   
3. Press the reserved salted egg yolk through the sieve into the mixing bowl.
   
4. Optionally, add some red food coloring. The lava center and the custard filling share a similar color. The food coloring will give some separation to different layers so the presentation looks nicer.
   
5. Mix well and pour the mixture through a sieve into a saucepan. Heat the mixture over low heat and stir constantly for 5-6 minutes or until the consistency becomes solid and separates from the bottom of the pan.
   
6. Transfer the milk yolk custard filling into a container. Cover well and chill it in the fridge overnight.
   
7. The next day, take the milk yolk custard filling out of the fridge and divide it into 16 even pieces, 18 grams each. Roll each one into a ball. Once done, cover them so they don't dry out.
   
8. Take the lava filling out of the freezer and pop them out of the mold.
   
9. Poke a hole in the middle of the custard filling and use it to wrap the lava filling. Do that to all 16 of them. The frozen filling will get soft as you are working. If you are slow, put some filling in the freezer and take them out gradually.
   
10. Once done, cover them and place them in the freezer for 2 hours. We are not trying to freeze them. We just want to keep them nice and cold. If the filling is warm, it will turn soft quickly in the oven and cause the mooncakes to collapse.
    

Make the wrapper (25g each, makes 16 wrappers)

1. Add the room-temperature unsalted butter and icing sugar into a big mixing bowl. Whisk them until fluffy. You could use granulated sugar, but it will take some time to whisk until dissolved.
   
2. Add whipping cream, egg yolk, salt, vanilla extract, and food coloring (optional), then whisk well.
   
3. Sieve in the cornstarch and cake flour. Switch to a spatula and mix until you don't see any dry flour. This will take only 2 minutes. Don't over-mix because we don't want the wrapper to be doughy.
   
4. Cover the dough and chill it in the freezer for 20 minutes or until firm and non-stick.
   
5. Divide the dough into 16 even pieces, about 25g each. Use a scale to be precise, then roll each one into a ball and cover them so they don't dry out.
   

Wrap the mooncakes

1. Take the filling out of the freezer. They are cold and firm but not rock hard, perfect for wrapping.
   
2. Grab a wrapper dough, poke a hole in the middle, and shape it into a small little bowl. Put a filling in and use your forefinger and your thumb to squeeze around and push the wrapper up. When you get to the very end, push and seal it completely.
   
3. Roll the mooncake in between your hands until nice and smooth. Set it aside. Do the same thing to the rest of the mooncakes.
   
4. I calculated this recipe with precise measurements. Lava filling (7g)+ milk yolk custard filling (18g) + wrapper (25g), making a total of 50g mooncake. Therefore, you will need a 50-gram mooncake presser. You can click this link to purchase it.
   
5. Brush the mooncake pattern with flour to prevent sticking. Coat a mooncake ball with a little bit of cake flour and shake off the excess. Shape the ball into a cylinder, then put it into the mooncake presser. Press it down onto a baking pan lined with baking paper. Stay there for a few seconds to establish the shape, then release it.
   
6. Do the same thing to all 16 mooncakes. If you don't have a mooncake presser, you can bake them round. The taste is the same. However, as a traditional dessert, they need a sense of ceremony.
   

Bake the mooncake

1. Preheat the oven to 360°F / 182°C. While waiting, quickly mix 1 egg yolk with 2 tsp of water.
   
2. Brush the egg yolk onto the surface of the mooncake, including the top pattern and the sides.
   
3. Stick the mooncakes into the oven and bake for 8 minutes.
   
4. Take the mooncakes out, and brush another layer of egg yolk.
   
5. Put the mooncakes back in the oven and bake for 6-8 minutes. Every oven is different. You should stay next to the heat and keep an eye on it. The filling is cooked already; we just want to cook the wrapper through.
   

6. Enjoy the mooncakes with tea. Happy mid-auttem festiavl.