Former Aberdeen manager Sir Alex Ferguson was present as a guest of the home club to mark the 50th anniversary of his hat-trick for St Johnstone in a 3-2 victory over Rangers.
But it was Aberdeen - the club he steered to domestic and European glory - who took the honours after a bright, enterprising display.
Pawlett had aleady gone close once before claiming his second goal of the season (18), a crisp left-foot finish after a nice back-heel by Scott Vernon.
Saints were struggling to make an impact in the final third but it needed a fine stop from Aberdeen goalkeeper Jamie Langfield to thwart Stevie May.
Alan Mannus had to be alert to deny Pawlett a second goal before Rory Fallon - one minute after coming on as substitute - collected the sixth red card of his career for an errant elbow on Michael Hector.
The Dons saved their best to last, as McGinn (85) embarked on a lung-bursting run from his own half before looking up and curling his shot past Mannus from the angle of the box.