In a large mixing bowl, cream together ½ cup of unsalted butter with ½ cup of brown sugar and ¼ cup of white sugar until light and fluffy, about 3-5 minutes. Beat in one egg and 1 teaspoon of vanilla extract until well combined. In a separate bowl, whisk together 1 ½ cups of all-purpose flour, 1 teaspoon of baking soda, and a pinch of salt. Gradually blend the dry ingredients into the wet mixture, forming a soft dough; chill in the refrigerator for 30 minutes to firm up.

While the dough chills, prepare the mango jam by finely dicing 1 ripe mango and placing it in a saucepan over medium heat. Add 2 tablespoons of granulated sugar and simmer for 10-15 minutes, stirring occasionally until the mixture thickens and becomes jam-like. Remove from heat, let it cool completely, and set aside for layering in the cookies.

Next, rinse 1 cup of sweet rice under cold water until the water runs clear. Soak the rice in water for at least 4 hours or overnight. Once soaked, steam it for 20-30 minutes until tender. Mix the rice with ½ cup of coconut milk and ¼ cup of sweetened condensed milk for added creaminess, then allow it to cool.

Preheat your oven to 350°F (175°C). On a parchment-lined baking sheet, scoop out dough balls about 2 tablespoons in size, spacing them 2 inches apart. Make a hollow in each ball, fill with mango jam, then top with sticky rice.

Bake for 12-15 minutes until golden brown with a soft center. Avoid overbaking.

Let cool on the baking sheet for 5 minutes before transferring to a wire rack.