What is the name of the cutter used to make butterfly fries or flutter fries?

Question

I'm looking to make these at home but I don't know what the special potato cutter is called. It spiral cuts the potato and leaves only a slim tube-shaped thin core behind. They're used to make "Butterfly" or "Flutter" fries. This is what they look like:

http://80sknight.homedns.org:8080/butterflyfries.jpg

Thank you! :)

Answer 1

you could use a butterfly cookie cutter

Answer 2

a mandoline