Question How to mask or hide UI with an image

To illustrate

I want the white image to be transparent but still hide the dark square, how can I do that?

I need it to only hide its linked image, since I'm gonna be stacking UIs on top of each other I only want it to affect a single thing, but I have no idea how to do it

I already searched but nothing seems to fit what I want here, unless I'm mistaken

I would appreciate any help