Steps
- Preheat the oven to 350°F / 175°C. Grease a 9 × 13in / 23 × 33cm baking pan. Whisk 3 cups of all-purpose flour, 1 teaspoon of baking powder, 1 teaspoon of baking soda, ½ teaspoon of ground cinnamon, and ½ teaspoon of salt together.
- Beat ¾ cup of softened unsalted butter, 1 cup of granulated sugar, and ½ cup of packed light brown sugar on medium-high speed for about 3 minutes.
- Beat in 3 large room-temperature eggs, 2 teaspoons of vanilla extract, and 1½ cups of mashed ripe bananas, scraping the bowl as needed.
- On low speed, add the flour mixture in three additions, alternating with 1½ cups of room-temperature buttermilk. Mix just until combined, leaving small lumps.
- Spread in the pan and bake for 45-50 minutes, until a toothpick comes out clean. Loosely cover with foil if the top browns too quickly, then cool completely in the pan on a rack.
- For the frosting, beat 226g of softened full-fat brick cream cheese with ½ cup of softened unsalted butter until smooth. Add 3 cups of confectioners' sugar, 1 teaspoon of vanilla extract, and ⅛ teaspoon of salt.
- Beat on low for 30 seconds, then on high for 2 minutes. Spread over the cooled cake and refrigerate for 30 minutes before slicing.