Mix white grass jelly powder with sugar and water until dissolved. Bring to a boil, cook for 1-2 minutes, then remove from heat. Pour into a mold and let cool.
Repeat the previous steps with black grass jelly powder, using the same amount of water and sugar.
When both of them have cooled, place them in a fridge for 2 to 3 hours and allow them to solidify.
Add the coconut milk, fresh milk, and condensed milk to a saucepan. Next, boil the mixture. Pour in 1 cup of water to reduce the milk mixture's fattiness. Cook for 1 to 2 minutes more, then cut the heat.
Soak basil seeds in warm water for 5 minutes. Check jellies for firmness, then unmold and cut into bite-sized pieces. Keep the two types separate.
Spoon the jellies into a bowl or glass and pour in the sweet soup. Add the basil seeds, and enjoy!