Is there any way to make a custom written shader with hdrp?

I made a new project and it uses HDRP, but then I realised I have to use one of my written shaders and so far that seems to be impossible with the HDRP asset on? If those shaders can't be used yet with it, then it's ok I'll just have to go without HDRP for a while, but I'd like a clarification before I mess something up.