Mix the flour, baking powder, milk, yogurt, egg, salt, and a little cooking oil together. Do not mix too long or too thoroughly, or the cake will be dense. Pour the batter into the rice cooker over the arranged bananas. Press the cook button as if cooking rice. Once done, check the cake; if it's not cooked, press the cook button again. Once the cake is done, invert it onto a plate, and it's ready.