Preheat oven to 350 degrees F..
Butter and flour two 9-inch round cake pans and line bottom of each pan with parchment paper or wax paper.
Sift together flour, baking powder, cinnamon, and salt and set aside. In a food processor or blender, process the milk and banana into a smooth light puree. Set aside.
In bowl of stand mixture, cream together the butter and sugar until light and fluffy. On medium high speed, beat in egg whites 1-2 at a time until smooth, scraping down sides of bowl between egg additions.
With mixer on low speed, add dry ingredients and banana puree alternately in 2-3 additions, beating until just blended. Scrape down the sides of the bowl and beat on medium-high speed for 1-minute. Divide batter among the cake pans.
Bake for about 25 minutes or until toothpick comes out clean when inserted into the center of each cake. Let the cake layers cool in the pan for 10 minutes and then turn out onto wired rack and remove the paper liners. Cool completely.
For whipped cream, beat together heavy cream and sugar until fluffy.
To assemble, put one layer, flat side up, on a cake stand or serving plate. Cover the top evenly with whipped cream and sliced bananas; place the second layer on top and press down until level.