• Prep – Preheat the oven to 175°C / 350°F. Grease and line a 9 x 13-inch baking pan with parchment paper.
• Dry ingredients – In a bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set aside.
  315 g All-purpose flour, 2 tsp Baking powder, 1 tsp Baking soda, ½ tsp Salt, 1 tsp Ground cinnamon, ¼ tsp Ground nutmeg
• Cream butter and sugar – In a large mixing bowl, beat the softened butter and brown sugar until light and fluffy, about 2 to 3 minutes.
  225 g Unsalted butter, 250 g Light brown sugar
• Add eggs – Add the eggs one at a time, mixing well after each addition. Then add the vanilla extract.
  3 large Eggs, 1 tsp vanilla extract
• Add bananas – Mix in the mashed bananas and sour cream until combined. The batter may look slightly curdled at this stage, which is normal.
  450 g Mashed ripe bananas , 180 g Sour cream
• Combine batter – Add the flour mixture and fold gently until just combined. Do not overmix.
• Bake – Pour the batter into the prepared pan and smooth the top evenly. Bake for 35 to 42 minutes, or until a skewer inserted in the center comes out clean.
• Cool – Let the cake cool completely in the pan before frosting.

Cream Cheese Frosting

• Make frosting – Beat the cream cheese and butter until smooth and creamy. Add the powdered sugar gradually, followed by the vanilla extract and salt. Beat until light and spreadable.
  340 g Cream cheese, 170 g Unsalted butter, 420 g Powdered sugar, 1 tsp Vanilla extract, pinch of salt
• Frost cake – Spread the frosting evenly over the cooled cake and sprinkle with chopped walnuts if desired.
  2 tbsp Chopped walnuts
• Serve – Slice and serve at room temperature.
  Light dusting of cinnamon