Install header only targets?

What is the correct way to install header only targets? Currently I’m doing something like this;

    DIRECTORY include/my_header_interface

Trying to do install(TARGETS my_header_interface) simply fails. Why is that?

Setting target properties PUBLIC_HEADER and installing that seems very clumsy.

I would also like to install my target only, e.g. ninja my_header_interface/install, but INTERFACE targets are not seen in ninja.

Is there an error message?

Install components are all that are provided generically for such things, sorry.