Add water in the pot of rice cooker and switch on the cooker. We have to boil the water.
In a bowl add maida, baking powder, baking soda, cinnamon powder, salt, nutmeg powder and sugar. Mix.
Add bananas after mashing them. Also add butter, oil & milk. Walnuts are to be added after tossing in a tsp of flour.
Mix everything well. If the dough is dry, add little more milk. Though we didn't need to add more than 1/4 cup. Remember, we have to make a dough which is gooey and sticky. Don't bring the mixture to the pouring consistency like batter.
Transfer the dough in a greased cake tin and tap the cake tin so that dough levels up.
By now, water in the rice cooker must have begin to boil. Place steam rack over the pot.
Place the cake tin and cover the lid.
Let the cake steam for 20 minutes. Check the cake using toothpick method.
Take the cake tin out and let it turn completed cool.
Invert, cut into slices and enjoy.