Preheat and prepare the pan

• Preheat the oven to 175°C (350°F).
• Grease and line a 20x20 cm baking pan with parchment paper.

Make the cinnamon sugar filling

• Mix 50 g of the brown sugar with 5 g of the cinnamon in a small bowl.
• Set aside for the swirl pockets.

Mix the wet ingredients

• Beat the softened butter with the remaining brown sugar and the granulated sugar until light and fluffy.
• Add the eggs one at a time, beating well after each addition.
• Stir in the mashed bananas, vanilla extract and sour cream until smooth.

Add the dry ingredients

• Whisk the flour, baking soda, baking powder, salt and the remaining cinnamon together.
• Fold the dry ingredients into the wet mixture just until combined — do not overmix.

Assemble the cake

• Pour half of the batter into the prepared pan.
• Sprinkle the cinnamon sugar filling evenly over the batter.
• Cover with the remaining batter and swirl gently with a knife to create cinnamon sugar pockets.

Bake

• Bake until a toothpick inserted in the center comes out clean and the top is golden.
• Let the cake cool completely in the pan.

Make the frosting

• Beat the softened cream cheese and butter until smooth.
• Add the powdered sugar, milk and a splash of vanilla, then beat until creamy and spreadable.

Frost and serve

• Spread the creamy frosting generously over the cooled cake.
• Slice and enjoy — soft, moist banana cake with cinnamon roll pockets.