Oil around oil cap

There is always oil residue around my oil filler cap. Even if I clean it with degreaser it's back after a few drives. I also sometimes have oil smell in the cabin after hard acceleration. The CCV and the complete valve cover is new, I also tried different oil caps and even used 2 gaskets in the cap to increase the pressure, but nothing really helped. Has anyone an Idea whats causing this?

325ti M54B25