In a mixing bowl, mash 2 ripe bananas using a fork or a potato masher until smooth.
Add 250 grams of rice flour, 50 grams of grated jaggery, 1/4 teaspoon of cardamom powder, and a pinch of salt to the mashed bananas. Mix well to form a smooth batter.
Gradually add 200 ml of water to the batter, mixing continuously to avoid lumps. The batter should have a pouring consistency similar to regular dosa batter.
Heat a non-stick tawa or dosa pan on medium flame. Once hot, pour a ladleful of batter onto the tawa and spread it evenly in a circular motion to form a thin dosa.
Drizzle 1 teaspoon of ghee around the edges of the dosa and cook for 1-2 minutes until the bottom turns golden brown.
Flip the dosa and cook the other side for another 1-2 minutes until golden brown.
Transfer the cooked banana dosa to a serving plate and repeat the process with the remaining batter.