The logbook is not an EASA rule, but without a logbook you will not get your licence! You can also create you own logbook or use/modify one of the samples below
UK-CAA CAP 741: Aircraft Maintenance Engineers Log Book - Sample
Austro Control: On - the - Job Training (OJT) Tasks List
Swiss Logbook with Detailed Tasks - Aircraft Maintenance Engineer's Basic Practical Logbook
documentation requirements for Part-66 basic licence applications when
experience is gained outside a Part-145 or Part-M approved maintenance
Work experience required to add another licence category.
OJT shall be performed on the aircraft type for which the applicant is seeking type endorsement. The objective of the OJT is to gain the required competence and experience in performing safe maintenance on that particular aircraft type.