Cook the beans: Drain the mung beans and transfer them to a small saucepan. Add the water and bring to a simmer over low-medium heat. Let simmer for 10-15 minutes, covered, until the beans are completely soft. Note: feel free to add a bit more water if no water remains and the beans are still firm.

Combine: Drain and transfer the cooked beans to a high-speed blender. Add the coconut milk, water, sugar, tapioca starch, rice flour, and vanilla extract. Blend for 10-15 seconds or until smooth. Transfer the batter to a bowl and set aside.

Prepare the pandan juice: Roughly chop the pandan leaves and add them to a blender. Add the water and blend on high-speed for about 30 seconds.

Strain the juice using a fine-mesh sieve and discard the pulp, only keeping the liquid. Note: the juice will smell very grassy. It is normal, the flavor will change after cooking.Transfer the juice to a large mixing bowl.

Combine: To the mixing bowl, add the coconut milk, sugar, tapioca starch, rice flour, and pandan extract if using. Whisk until fully combined. Set aside.

Prepare your setup: Fill a saucepan with 2-3 cups of water and place a bamboo steamer on top. Bring the water to a boil. Lightly grease a 3x6-inch pan (you will have enough batter for two pans) with oil and place it in the steamer for 2 minutes.

Steam the first layer: Pour one layer of the green batter into the pan and steam for 3 minutes. I went with 3 tablespoons of the batter to get thin layers. Adjust depending on the size of your pan.

Steam the second layer: Pour the same amount of the yellow layer over the green layer. Steam for 4 minutes.

Repeat. Repeat the process until you have about 7 layers (you can do more). For each layer, increase the steaming time by one minute.

Finally, after steaming the last layer, let the whole cake steam for an extra 7 minutes.

Let cool: Remove the pan from the steamer and let the cake cool completely before removing it from the pan.

Slice: Using a sharp knife with the blade wrapped in plastic wrap (to prevent sticking), cut each loaf into 5 rectangles. Enjoy as a snack!