Take ragi flour, cocoa powder, baking powder and baking soda in a sieve
Sieve them 5-6 times and keep it ready
Take ripe bananas and mash them. You can use blender too.
Add milk to bananas
Then add sugar, oil, vanilla essence and vinegar.
Mix it nicely with hand whisk till everything is combined
Then add flour in batches and mix it till everything is combined without lumps
Add chopped walnuts or any nuts of your choice to the batter.
Grease the baking tin with butter and dust with little flour.
Pour the batter to greased tin and tap the tin to release air
Preheat the oven to 180°C and bake in the same temperature for 35-40 minutes
Remove from oven and cool the cake completely in wire rack and slice them.
Enjoy cake with Tea/Coffee