Firstly, preheat the oven to around 360 degrees. Then grease the 8″ pans.
Add sugar and butter into a bowl and beat them until they turn into a creamy mixture.
Take the banana in a different bowl and then mix it with the buttermilk. Make an even mixture.
In another different bowl, sift wheat flour, white flour, baking powder, baking soda, and salt and mix them well.
Pour ⅓ of the wheat mixture into the butter mixture, then add ½ of the banana mixture into the mixture, then add ⅓ flour mixture again, and finally add the rest of the flour and butter mixture. Do this to get an even mixture of everything. Beat the whole mixture until everything is mixed evenly.
Add ½ of the mixture to one pan and the other ½ of the mixture in a different pan. Then bake them for about 30 minutes.
To check if the cake is ready, insert a wooden toothpick into the cake. If it comes out clean, the cake should be ready.
Before you freeze the cake, make sure the cake is down to room temperature or close to room temperature.
Make a chocolate frosting for preparing the cake.
Frost one of the two layers, place a banana on top of it and then place the other layer on top of it.
Now coat both sides and the top of the cake with the rest of the frosting.