Prepare the Mango Jam by heating frozen mangoes in a saucepan over medium heat for 5-7 minutes, mash with a fork, mix in white sugar, and let cool.

Cook the Sticky Rice by soaking sweet rice in boiling water for at least 30 minutes, draining, and steaming for 20 minutes, then mixing in coconut milk and sweetened condensed milk.

Make the Cookie Dough by creaming unsalted butter, light brown sugar, and white sugar until fluffy. Add egg yolk, thick egg white, vanilla, and reserved coconut cream, then mix in baking soda, salt, and flour gently.

Assemble and Bake by preheating the oven to 350°F (175°C), folding in mango jam and sticky rice into the dough, scooping onto a baking sheet and optionally topping with black sesame seeds.

Final Bake for 13-15 minutes until edges are golden brown. Let cool on the tray for a few minutes before transferring to a wire rack.