Choose the jackfruit leaves that are big and even in size. You need 4 leaves for making one cup like structure(kotte). Using cocunut leaflet midrib stitch 4 leaves together as shown below.

Next bend leaf in "L" shape and fix it with adjacent one.

Bending and stitching each leaf with it's adjacent one has to be repeated till you obtain cup like structure.

Following this procedure get all the cups ready. You can make them a day ahead too. I have cut the extended stem for neat presentation.

Wash and soak the blackgram lentils for about 2 hours.

Drain all the water from lentils and grind it to light and airy batter adding required water. You can use wet grinder if you have one.

Soak idli rava in enough water for about 20 minutes. Squeeze and add the rava to lentils batter. Mix and let it rest for about 8 to 10 hours for fermentation.

After fermentation the batter would have raised up. Add required salt an mix well. Now batter for kotte kadubu is ready.

Next carefully pour the idli batter in to jackfruit leaf cup prepared earlier. Arrange batter filled cups in a idli-steamer and steam cook for about 15-20 minutes.

Insert a spoon in to cooked idli to check for doneness. If it comes out clean, it's done.

Remove all the sticks used to stich the cup and serve idli along with chuntey and sambar of your choice.

Ensure the jackfruit leaf cup isn't leaking. If you follow the video, the cup turns perfect with no holes.

Keep them ready before-hand to save time in the morning.

Grinding the batter using wet grinder yields light, airy batter with good volume. So use it if you have one.

I have used idli rava instead of grinding rice. You can use rice too. In that case, soak rice, grind coarsely and mix with lentils batter.

Give the batter enough resting time for better fermentation. In warm places 8 hours of fermentation is enough.

You can keep as many cups as your steamer can hold and steam them all together.