In a mixing bowl, combine softened unsalted butter and icing sugar.
Add whipping cream and egg. Mix until well combined.
Stir in the black sesame paste until fully incorporated.
Sift in all-purpose flour and cornstarch. If available, you can use 120g of cake flour instead. Gently use the cut and fold method to blend until a dough forms.
Wrap the dough with plastic wrap and refrigerate for at least 1 hour.
To assemble black sesame lava mooncakes
Allow the cookie crust dough to reach room temperature for 30 minutes.
Divide the dough into 25-gram portions and roll each into a ball.
Divide the black sesame custard filling into 20-gram portions and roll each into a ball.
Take out the black sesame lava filling from the mold. Flatten the black sesame custard dough, place a piece of lava filling in the center, seal it, and roll it into a ball. Repeat for the remaining fillings.
Flatten the cookie crust dough into a disk shape.
Wrap the filling with the cookie crust dough, sealing the edges securely.
Lightly coat it with all-purpose flour, shaking off excess. Sprinkle flour onto the mooncake mold.
Place the filled dough into the mold to create a pattern.
Air fry at 290°F for 7 minutes. Allow it to cool in the basket before transferring to an airtight container. Ready to serve.