Cake:

• Preheat oven to 350℉ / 177℃
• Prepare an 8" round cake pan by lining the bottom with parchment paper or greasing the pan.
• Smash one banana and set aside.
• Whisk flour, baking powder, salt and cinnamon in a small bowl.
• Place butter and granulated sugar bowl of a stand mixer. Using the paddle attachment, begin mixing the butter and sugar until light and fluffy (2 - 4 minutes), scraping sides and bottom of bowl occasionally. (note: a hand mixer may also be used).
• Add room temperature eggs, one at a time, scraping sides and bottom of bowl between each addition. Mix on medium-low speed until eggs are well incorporated.
• Add rum and mix for approximately 30 seconds,
• Add smashed banana and mix for approximately 60 seconds.
• Add flour mixture and mix on low speed until just combined.
• Pour half of the batter into prepared pan. Slice 2 bananas in ¼" slices and layer on top of cake batter.
• Pour second half of cake batter over bananas and smooth top with an offset spatula.
• Sprinkle 2 tablespoons of granulated sugar evenly over top of cake.
• Bake for 50 - 60 minutes at 350℉ / 177℃. The cake top will be a golden color and a toothpick inserted in the center of the cake will come out clean when the cake is done.
• Place cake on a rack and allow to cool completely before unmolding.
• If desired, sprinkle confectioners' sugar over top of cake after unmolding.