Step 1

Preheat your oven to 180°C/ 350°F (fan-forced). Line a slice tin with baking paper.

Step 2

In a food processor or blender combine the butter, eggs, banana and blend until smooth. Thermomix, 10 seconds, speed 6.

Step 3

Add the milk, bicarb and salt and blend again.  Thermomix, 10 seconds, speed 6.

Step 4

Fold in the flour until just combined and pour into a lined slice tin. Thermomix, flour symbol, two rotations.

Step 5

In a small bowl, mix all of the swirl ingredients together with a spoon until combined.

Step 6

Blob on top of the cake batter and  swirl through gently to semi combine (it is quite a thick mixture but does blend into the cake batter with a gentle stir).

Step 7

Bake for 15-20 mins or until it is firm to touch in the middle. Allow to cool on a rack and slice.

Step 8

Store in an airtight container in the fridge or freezer.