Never an easy thing to do. Different reasons as to why attendings do this - perhaps lazy, perhaps because they forget memories working with you.
This will continue during residency and beyond for some folks so good to have an idea of what to do.
1) You want to make this as specific as possible about your interactions with the attending. E.g., "Omi gave a presentation on hypercalcemia that was ____ and gave credibility to his ____ of patient XXX" "Omi arrived at Pulmonary tumor board ready to participate and did so as follows...I was impressed because ...." Specific, concrete examples are essential here.
2) No over-embellishing yourself. E.g., "Omi was the greatest student that ever lived. Patients will pay double to see him."
3) Ask secretary for official letterhead, provide all the details to said attg on submission, etc.