It looks like a star-shaped driver, unusual type you aren't likely to have at home.

See, the plan is you tighten this weird screw exactly once, then lose the driver. It's designed to stay tight 18 months. That's about when you've beaten up the surface and overheated it until it's no longer stickproof. Then the handle gets loose and you get fed up and go buy another pan.

I actually like this plan when Home Goods has decent replacements like Calphalon for $25. Except Calphalons don't fall apart and they already come assembled. You can burn 'em out tho.