Yes, please click on the Karma score (at the top) and then "View All Completed". This will show you all tasks completed in all projects, sorted by date and time + some options to filter this list by timeframe, project and label.
Wonderful! Is there any way to print that completed list?
That's also possible - click on the gear icon at the top and choose "Print current page". It will always print any view that you're currently in, in this case - the list of completed tasks.