Slice the butternut in half. Using a vegetable peeler or electric slicer, slice thin ribbons of butternut.

Preheat the oil and deep-fry the butternut ribbons until crisp. Remove and drain on absorbent paper.

Season with salt and rosemary.

The crisps can be made the day before using and kept in a dry place or airtight container, but are best prepared on the day.