Preheat the oven - Set the oven rack in the middle of the oven and preheat to 350°F.
Prepare the baking pan - Line 15 muffin cups from 2 standard size muffin pans with cupcake liners and set aside.
Prepare wet ingredients for the banana cake - Mash the bananas with a potato masher in a large mixing bowl. Add miso paste, oil, eggs and vanilla, and beat with a whisk until thoroughly combined.
1 ⅓ cup mashed banana, 3 tablespoon white miso paste, 3 oz vegetable or canola oil, 2 large eggs, 1 teaspoon pure vanilla extract
Add sugar - Add brown sugar and beat again until completely incorporated.
¾ cup brown sugar
Add dry ingredients - Sift flour, baking soda and baking powder directly into the bowl with the wet ingredients. Mix gently with a whisk or a spatula until combined and no trace of flour remains.
1 ¾ cup all-purpose flour, ½ teaspoon baking soda, 1 teaspoon baking powder
Bake - Divide the cake batter equally among 15 lined muffin cups and bake in the preheated oven for approximately 15 minutes, until a toothpick inserted into the center of the cake comes out clean with just a few crumbs attached.
Cool - Remove the cupcakes from the oven and let cool completely on a wire rack before adding frosting.
Make the frosting – Add room temperature cream cheese, butter and vanilla extract to your stand mixer bowl, fitted with the wire whisk. Sift in the powdered sugar and ground cinnamon. Stir to incorporate the powdered sugar at first. Then gradually increase the mixer speed to combine all the ingredients. Refrigerate as needed if the frosting seems too loose before beating until fluffy.
12 oz cream cheese, 6 oz unsalted butter, 1 teaspoon pure vanilla extract, 1 ¼ cup powdered sugar, 1 tablespoon ground cinnamon
Beat until fluffy – Beat on medium high speed for just a minute or two until the frosting is fluffy and creamy. Give it a taste and stir in more powdered sugar if a sweeter frosting is desired. Don’t overbeat cream cheese frosting or it will separate.
Add frosting to cupcakes - Spread frosting evenly on top of the cooled cupcakes with an offset spatula or pipe it on with a pastry bag fitted with a piping tip. Decorate with banana chips if desired. Serve and enjoy!
Notes
Thaw frozen bananas: if you’re using frozen bananas like me, make sure they thaw completely and just mash them up along with the liquid that comes out as they thaw. No need to strain.
Choose low sodium miso paste: the white miso paste I used in this recipe has 290 mg of sodium per tablespoon. Check the nutrition label when you pick out your miso paste. The brand I used is Marukome. If your miso paste has a higher sodium level, you may need to adjust the amount to prevent the cake from being overly salty. Keep the total sodium from miso paste to around 900 - 1000 mg.
Storage: store your miso banana cupcakes in the fridge for 3-5 days. Or freeze leftovers, individually wrapped, for up to 3 months. Let come up to room temperature before serving.