Prepare Mango Jam: Dice ripe mangoes, place in a saucepan, add sugar, and cook over medium heat for 10-15 minutes until thickened. Allow to cool.

Make Sticky Rice: Soak sweet rice for 4 hours, then steam over cheesecloth for 20-30 minutes. Combine with coconut milk and condensed milk, then cool.

Prepare Cookie Dough: Cream butter, brown sugar, and white sugar until fluffy. Blend in egg and vanilla, then add dry ingredients to form dough. Chill for 30 minutes.

Assemble Cookies: Preheat oven to 350°F. Shape chilled dough into balls, create a hollow, fill with mango jam, and top with sticky rice. Press gently to secure.

Bake: Place on a baking sheet and bake for 12-15 minutes until golden brown at edges. The center should be soft.

Cool: Let cookies rest for 5 minutes on the sheet, sprinkle with sea salt, then cool completely on a wire rack.