Do

1. Line a 20x20cm tin with baking paper.

2. Place butter into the Thermomix bowl. Melt 2 min/70°C/speed 1

3. Add sugar, cocoa, salt and vanilla. Mix 20 sec/speed 4. Add eggs one at a time while mixing 20 sec/speed 4.

4. Add cornflour and combine 12 sec/Interval/dough setting. Scrape batter into prepared tin. Dollop the caramelised dulce de leche on top and swirl through using a fork.

5. Bake for 30 minutes. Sprinkle with salt flakes whilst still hot. Cool in tin.

6. This stores very well in the freezer and will keep up to 3 weeks in the fridge if kept in an airtight container.