Drain the soaked glutinous rice through a fine-mesh sieve and spread it into a bamboo steamer lined with cheesecloth, or a saucepan steamer insert.

Steam over boiling water for 20 to 25 minutes, covered, until the grains are translucent and tender with no white core. Check by pressing a grain between your fingers.

While the rice steams, combine 180 ml coconut milk, palm sugar, and 1/4 tsp salt in a small saucepan over low heat. Stir until the sugar dissolves, about 2 minutes. Remove from heat.

Transfer the hot steamed rice to a mixing bowl. Pour the warm coconut milk mixture over the rice and fold gently to combine. Cover with a plate and let sit for 10 minutes so the rice absorbs the liquid.

Combine the remaining 60 ml coconut milk with the remaining 1/4 tsp salt in a small saucepan over low heat. Stir for 1 to 2 minutes until just warmed through. Set aside.

Allow the coconut rice to cool to room temperature, about 15 minutes. It should be slightly sticky and glossy, not wet.

Spoon a generous layer of coconut rice into the bottom of each glass, about 4 to 5 tbsp per glass. Press gently to level.

Arrange a layer of mango planks on top of the rice, leaning them against the glass wall so they're visible from outside.

Add another thinner layer of coconut rice on top of the mango, then finish with a final layer of mango planks at the top.

Drizzle 1 to 2 tsp of the salted coconut topping cream over each parfait. Scatter toasted sesame seeds on top and add a mint sprig if using. Serve immediately or refrigerate for up to 4 hours before serving.