Preheat your oven to 180C.

Start by browning your butter. Place the butter into a small saucepan over a medium heat and melt the butter. Let it bubble away until the butter turns brown – don't take it too far. Add the vanilla extract and leave to cool slightly.

Meanwhile, in a stand mixer, whisk the eggs and muscovado sugar until light and frothy.

Melt the chocolate slowly in the microwave to prevent burning.

Once the chocolate has melted, whisk in the cooled brown butter, before pouring into the egg and sugar mixture.

Mix thoroughly before stirring in the hazelnuts and cocoa powder.

In a separate bowl, mash the banana with a fork and stir in the caramel.

Mix half of this mixture through the brownie mixture and leave some aside.

Pour the mixture into a 30x20cm baking tin lined with greasproof paper and spread level.

Marble in the remaining banana and caramel mixture and bake for 30 minutes – there should be a slight wobble to the finished brownie.

Ideally leave to cool overnight before eating!