1cup(200g) firmly packed light or dark brown sugar
1cup(120g) powdered sugarsifted
½cup(55g) chopped pecans
Preheat the oven to 350° F (177ºC). Grease and flour (or use homemade cake release) a bundt pan4. Set aside.
Measure the sifted cake flour into a medium size mixing bowl, then add the baking powder, cinnamon, and salt and whisk to combine. Set aside.
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, combine the butter, brown sugar, granulated sugar, buttermilk, eggs, vanilla, and rum, and beat on medium speed until everything is combined.
Reduce the mixer speed to low, then gradually add the dry ingredients in two additions, alternating with the bananas, to the wet ingredients. Continue mixing until the batter is smooth. Add the pecans, if using, and beat on low again until just dispersed.
Pour the cake batter into the prepared pan. Bake the cake for 45-50 minutes or until a toothpick inserted in the center of the cake comes out mostly clean. If using a bundt pan, allow the cake to cool for about 20 minutes before turning it out onto a serving plate.
PECAN PRALINE ICING
In a medium-sized saucepan, melt the butter over medium heat. Add the brown sugar, stir it together, and bring the mixture to a boil.
Boil the mixture for exactly 2 minutes, stirring continuously. Carefully add the rum5 and bring back to boiling.
As soon as the mixture is boiling again, remove it from the heat and add the powdered sugar. Stir until smooth, then add the pecans and stir until combined.
Working quickly as the icing will start to thicken6 as it cools, pour the icing evenly over the cake. If it becomes too stiff, warm it again. Allow the icing to set, then slice and serve. This cake can be served slightly warm or at room temperature. Store leftovers covered at room temperature up to 3 days or in the refrigerator up to 5 days. Cake freezes well, up to 3 months. Thaw in the refrigerator overnight.
Cake flour: if you don't have or don't want to use cake flour, use 3 cups of all-purpose flour less 6 Tablespoons (360g - 45g = 315g) and replace the 6 Tablespoons of flour with 6 Tablespoons of cornstarch (49g).
Sifting flour: sifting flour aerates it and increases the volume. Do not measure and then sift. If you are using all-purpose flour + cornstarch, you will still want to sift that mixture and then measure.
Rum: I used a dark spiced rum. If you don't want to use rum, consider water, apple juice, apple cider, or 1 Tablespoon of rum extract + liquid substitution to desired measurement.
Cake pan: you can also use a 9x13" baking pan for this cake.
Adding the rum: the mixture will bubble up. Add with caution.
Making the icing: I recommend waiting until you are ready to put the icing on the cake to start making it, as it thickens very quickly as it cools. If you choose to make it ahead of time, you will need to reheat it to get it to a viscous state again.