Instructions:
- Prepare & Preheat: Grease and line two 9-inch round cake pans with parchment paper circles. Preheat oven to 350°F (175°C).
- Combine Dry Ingredients: Whisk together flour, baking soda, baking powder, salt, cinnamon, and nutmeg in a medium bowl. Set aside.
- Cream Fats & Sugars: Cream the softened butter, brown sugar, and white sugar together using an electric mixer until the mixture is light and fluffy (about 3-4 minutes).
- Add Eggs & Vanilla: Beat in eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in 2 teaspoons of vanilla extract.
- Mix Wet Ingredients: In a separate bowl, combine mashed bananas, sour cream/yogurt, and buttermilk.
- Alternate Mixing: Gently fold in one-third of the dry ingredients into the butter mixture. Follow with half of the wet banana mixture. Repeat until all ingredients are just combined—do not overmix.
- Bake: Divide batter evenly between prepared pans. Bake for 50–60 minutes, or until a skewer inserted into the centre comes out clean.
- Cool Cake Layers: Cool the cakes in pans for 15 minutes, then invert onto wire racks to cool completely before frosting.
- Brown the Butter (Frosting Base): Melt 1 cup of butter in a light-coloured saucepan over medium heat, swirling frequently, until brown specks form and the butter smells nutty (about 5-7 minutes). Immediately pour into a heatproof bowl to cool to just warm/room temperature.
- Whip Cream Cheese: Beat the cold cream cheese until smooth.
- Assemble Frosting: Gradually beat in the cooled brown butter until smooth. Slowly add sifted powdered sugar, 1 teaspoon vanilla, and a pinch of salt until the frosting is light and spreadable.
- Frost: Once cakes are fully cooled, layer and frost the Banana Cake generously.