Sift the matcha into a small bowl. Add the hot water and whisk until completely smooth and no lumps remain.

In a saucepan, combine the agar agar powder, sugar, and 2 cups water. Bring to a boil, stirring to help the agar and sugar dissolve. Add the whole milk and prepared matcha, then stir until smooth and evenly combined.

In a separate small saucepan, combine the agar agar powder, sugar, and 1 cup water for the milk layer. Bring to a boil, stirring until dissolved. Add the milk and stir until smooth and fully combined.

Pour half of the matcha mixture into your mold or bowl of choice. Allow it to set for about 5–7 minutes, or until the surface is firm enough to support the next layer.

Gently pour the milk mixture over the first matcha layer. Let it set for about 8–10 minutes.

Pour the remaining matcha mixture over the milk layer to create the final layer.

Allow the jelly cake to cool to room temperature. Cover and refrigerate for 1–2 hours, or until completely chilled and set.

Remove from the mold if desired, then slice and serve chilled.