Prepare the Mango Jam by heating 2 cups of frozen mangoes in a medium saucepan over medium heat for 5-7 minutes. Mash with fork and mix in 1/2 cup of white sugar until jam-like. Cool in the fridge.

Cook the Sticky Rice by soaking 1 cup of sweet rice in boiling water for 20 minutes. Drain and steam for 30-40 minutes. Mix sticky rice with 1/2 cup of coconut milk and 1/4 cup of sweetened condensed milk.

Make the Cookie Dough by creaming together 1/2 cup unsalted butter and 3/4 cup light brown sugar for 2-3 minutes. Add egg yolk, egg white, vanilla, and reserved coconut cream. Mix in baking soda, salt, and all-purpose flour until just combined.

Chill the Dough by wrapping in plastic wrap and refrigerating for 30 minutes. Preheat oven to 350°F (175°C) and prepare baking tray.

Assemble and Bake by scooping tablespoon-sized portions of dough, flattening on the baking tray, adding mango jam and sticky rice. Bake for 13-15 minutes until edges are golden.

Cool and Serve by allowing cookies to cool on the baking tray for 10 minutes, then transfer to a wire rack to cool completely.