QM/MM tutorial for binding free energies

Dear Gromacs users,

I was wondering if you are aware of any well-established tutorials/protocols that have been written/published to calculate protein-ligand binding free energies in Gromacs, where the ligand is treated quantum-mechanically and the rest of protein-water system is MM?

While there are quite a few tutorials out there, none of them seem to be specifically tailored towards calculating binding free energies.

This is something I am looking for to implement in my research.

Many thanks,