Rinse the glutinous rice thoroughly under cold running water until the water runs clear. Soak the rice in plenty of cold water for at least 4 hours, or preferably overnight.

Drain the soaked rice well. If using a rice cooker, place the drained rice in the cooker and add 1 1/4 cups of water. Cook according to your rice cooker's instructions for white rice. If cooking on the stovetop, combine the drained rice with 1 1/2 cups of water in a saucepan. Bring to a boil, then reduce heat to low, cover, and simmer for 15-20 minutes, or until the water is absorbed and the rice is tender. Let it steam, covered, for another 10 minutes off the heat.

While the rice is cooking, prepare the coconut milk mixture. In a separate saucepan, combine 1 cup of the full-fat coconut milk, granulated sugar, and salt. Heat over medium-low heat, stirring constantly, until the sugar and salt are completely dissolved. Do not boil. Remove from heat.

Once the rice is cooked and has steamed, transfer it to a bowl. Pour about two-thirds of the warm coconut milk mixture over the hot rice. Gently fold the mixture into the rice until well combined. Cover the bowl and let it sit for at least 20-30 minutes, allowing the rice to absorb the coconut milk and become creamy.

Prepare the coconut cream topping. In a small saucepan, gently heat the reserved 1/4 cup of coconut cream (the thick part) with a pinch of salt. Stir until smooth and slightly thickened. Do not boil. Set aside.

Peel and slice the ripe mangoes. Aim for even slices or cubes.

To serve, spoon a generous portion of the sweetened sticky rice onto each plate. Arrange the fresh mango slices alongside the rice. Drizzle the warm coconut cream mixture over the rice and mango. Garnish with toasted sesame seeds, if desired.