Trying to convert files without changing the filenames

Hi! So it's the simplest thing I'm trying to achieve. I have a bunch of CBZ files that I'm trying to convert to PDF. The CBZ file names are all perfectly fine, I simply want to convert them to PDF. I have a file "Book123.CBZ" and I want to convert it to "Book123.PDF" but Calibre is insistent upon renaming the file to include a bunch of other stuff.

How do I get Calibre to just convert the files and keep the original file name?