Brown the butter

• Melt the butter in a light-coloured saucepan over medium heat.
• Keep cooking, swirling, until the milk solids turn golden brown and it smells nutty.
• Pour into a bowl and let it cool completely.

Make the banana cake batter

• Whisk the mashed bananas with the brown sugar, granulated sugar, eggs and vanilla.
• Stir in the cooled brown butter and the sour cream until smooth.
• Fold in the flour, baking soda, baking powder, salt and cinnamon just until combined.

Bake

• Pour the batter into a lined cake pan and smooth the top.
• Bake at 175°C until a skewer comes out clean.
• Cool completely in the pan, then turn out onto a rack.

Brown butter cream cheese frosting

• Beat the softened cream cheese and browned butter until creamy.
• Add the sifted powdered sugar and beat until silky and smooth.

Frost and finish

• Spread the frosting generously over the cooled cake.
• Drizzle with salted caramel sauce and sprinkle with flaky sea salt.
• Slice and serve.