Prepare the oven and pan

• Preheat the oven to 180 °C.
• Grease and line the cake pan.

Make the plantain cake batter

• Beat the softened butter with the brown sugar until pale and fluffy.
• Beat in the eggs one at a time, then stir in the mashed plantains and vanilla extract.
• Fold in the flour, baking powder, cinnamon and salt, then loosen with the milk until smooth.

Bake the cake

• Pour the batter into the prepared pan and level the top.
• Bake until a skewer comes out clean.
• Leave to cool in the pan, then turn out onto a cooling rack.

Cook the salted caramel

• Melt the granulated sugar in a saucepan over medium heat until a deep amber caramel forms.
• Off the heat, carefully stir in the warmed cream and the salted butter until smooth.
• Stir in the flaky sea salt and let cool slightly.

Make the brown sugar Swiss meringue

• Whisk the egg whites, light brown sugar and cream of tartar in a bowl set over simmering water until the sugar dissolves and the mixture reaches about 70 °C.
• Transfer to a clean bowl and whisk to stiff, glossy peaks.

Assemble and decorate

• Spread the salted caramel over the cooled cake.
• Pipe or swirl the brown sugar Swiss meringue on top.
• Finish with crushed plantain chips and a pinch of flaky sea salt.