Replace toilet flange on cast iron

I am replacing the floor in the second story bathroom and the current height of the flange is not high enough. Currently it looks like some something made of PVC with a metal ring inside the iron hub. I've attached pictures, sorry not the best and I know I should have cleaned the rest of the wax seal off. (Or cleaned more in general) My question is, what is the best way to raise the height with this setup, replace, extend? I need about 1/2 of an inch.

Thank you!

Brendan

I, and most plumbers, would break the flange off and install a new cast iron one. I am not sure how you should do it, because i don't know your abilities.

The plastic was just from the the wax ring which pulled right out when I cleaned off the wax. It is actually a metal flange attached to the inside of the cast iron. It is on there very solid and looks to be in good shape. I will attach new pics. Is it possible to add height to this? In all of my searching through the forums I havent found anything like this so I dont know what it is properly called.

I also don't "know what it is called" because I don't know how they could have attached that flange to a cast iron pipe.