1/3cupbuttermilk, well-shaken *see Note 1 below for DIY buttermilk
2mediumripe bananas, peeled and mashed (about 1 cup)
1teaspoonfresh lemon juice
For the banana buttercream icing:
2Tablespoonsbutter, softened
1/4cupripe banana, mashed
1/4teaspoonfresh lemon juice
1/2teaspoonvanilla extract
Pinchsalt
1 3/4 - 2cupsicing/confectioners' sugar
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Instructions
Preheat oven to 350F (regular bake setting/not fan-assisted). Grease an 8x8 inch baking pan, then line it with a sheet of parchment paper that covers the bottom and two sides, extending over the top of the pan slightly. Set aside.
In a medium bowl, combine the flour, baking soda and salt. Whisk to combine well then set aside.
In a large bowl with an electric mixer or the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, white sugar and brown sugar at medium speed until light and fluffy, about 2 minutes. Add the egg and beat it in well. Mix in the vanilla.
Add the flour mixture alternately with the buttermilk until combined. Stir in the mashed bananas and lemon juice.
Spoon the batter into the prepared baking pan and spread to level.
Bake for 25-35 minutes or until golden on top, the sides of the cake have pulled away from the side of the pan and a tester inserted in the centre of the cake comes out clean.
Remove from oven and allow the cake to cool completely in the pan before topping with icing. Tip! Make sure the cake is cooled completely! Even the slightest bit of warmth in the cake will melt the icing. You can refrigerate the cake in the pan to cool it more quickly.
When the cake is completely cool, prepare the icing. Using a bowl and an electric mixer or a stand mixer fitted with the paddle attachment beat together the butter, banana and lemon juice on medium speed until well combined. With the mixer on low, add the icing sugar and mix in, then increase the speed of the mixer to medium and mix until light and fluffy. Tip! You can adjust the consistency of the icing by adding additional icing sugar (if too thin) or a splash of milk (if too thick). You want the icing to be spreadable, but thick enough to hold its shape.
With the cake still in the pan, spread the icing onto the cooled cake. For a pretty presentation, use an icing spatula and run the rounded end through the icing in parallel lines, leaving a ridge in between the lines.
I like to cover and refrigerate the cake in the pan at this point. I enjoy this cake cold from the fridge and it also keeps longer if refrigerated. For longer storage, cut into squares and freeze for up to 3 months. Thaw the cake slices at room temperature for about 1 hour to enjoy.
Notes
Note 1: I always suggest using real buttermilk when possible. If you can't, you can substitute regular milk that has been soured with lemon juice or white vinegar. For the 1/3 cup required for the base recipe, add 1 teaspoon of lemon juice or white vinegar to 1/3 cup of regular milk and let stand for 10 minutes.If you are a lover of sweet and salty, try sprinkling a bit of flaky salt (such as Maldon's) on top of the icing.For a less-sweet icing, reduce the icing sugar to make more of a thick glaze. It's not as pretty, but it will be less sweet overall.Need to feed a crowd? Double the recipe and bake it in a 9x13-inch pan.Be sure to read the notes above this Recipe Card for more tips on making this recipe. You'll also find step-by-step photos that you might find helpful.