Try
@nodeselect
@nofilenamequoting
@runonce:@set dirname={filepath|\}OCR-files
@runonce:@set relpath={filepath|..|noroot|noterm}
CreateFolder NAME="{$dirname}\{$relpath}" READAUTO=no
"path\to\tesseract.exe" "{filepath}" "{$dirname}\{$relpath}\{file|noext}.txt"