Jim Leishman worked his magic to lift Dunfermline off the foot of the SPL table and swap places with Dundee.
The Pars ran riot at East End Park
The temporary manager watched Derek Young prod his side in front after just two minutes and the midfielder added a second from a rebound on the half hour.
Callum McDonald diverted an effort from Darren Young into his own net and Andrius Skerla's header made it four before half-time.
Young completed his hat-trick with a neat header in the 64th minute.
Dunfermline and Dundee are level on 31 points but the heavy defeat has put a large dent in the visitors' goal difference.
The kick-off was delayed by five minutes to allow the fans outside to take their seats and it proved to be well worth the wait for the home supporters.
Dunfermline opened the scoring after just two minutes thanks to a blunder by Dundee goalkeeper Derek Soutar.
The youngster spilled a header from Andy Tod and the ball bounced off defender Bobby Mann before falling kindly to the feet of Derek Young to stab home from a few yards.
The home side came close when Lee Makel's 25-yard curling free-kick whistled narrowly wide.
Dundee threatened when Stephen Robb's cross met the head of Mann and his effort was just over the crossbar.
Dunfermline goalkeeper Derek Stillie then pulled off a great save to prevent Mann's point-blank header finding the back of the net.
More poor defensive display led to Dunfermline's second goal in the 29th minute.
Derek Young won the battle for possession with McDonald and his initial shot came off Soutar, but both defender and goalkeeper were slow to react and Young was allowed time to prod home the rebound.
Leishman was given a warm reception from the home fans
It was proving to be a bad day for McDonald when he inadvertently added to Dunfermline's goal tally.
Darren Young tried his luck with a shot which looked like it was going well wide, but McDonald poked a leg out to clear and sent the ball into the back of the net instead in the 33rd minute.
Dunfermline thrilled the home fans further when a Lee Makel cross was met by Skerla, who sent a superb header past Souter six minutes before the break.
Derek Young scored his third goal of the day when Soutar was again found wanting.
The former Aberdeen man won the aerial battle with the 'keeper to send a back header into the back of the net.
He could have added to his own personal tally for the day again had his superb overhead kick not been disallowed for a foul on Soutar.
And the same player was denied by a good Soutar block after bursting into the Dundee penalty box.
Dunfermline: Stillie, Skerla, Scott Wilson, Scott Thomson (Labonte 71), Campbell, Darren Young, Mason, Makel, Derek Young (Hunt 79), Tod (Mehmet 63), Craig Wilson. Subs Not Used: Langfield, Donnelly, Dunn, Ross.
Booked: Skerla, Hunt, Darren Young. Goals: Derek Young 2, 29, McDonald 33 og, Skerla 39, Derek Young 64.
Dundee: Soutar, McNally (Larsen 79), Mann, McDonald, Robb, Brady, Fotheringham (Robertson 79), Smith, Anderson, Lovell (Barrett 86), Caballero. Subs Not Used: Dubourdeau, Clark, Conway.
Booked: Lovell, Fotheringham.
Ref: A Freeland