The striker, who became just the eighth man in the tournament’s history to score four times in one game, displayed just how he has scored 33 goals this season at an average of a goal a game.
Bayern, who thrashed Hoffenheim 7-1 at the weekend, came into this game with a 1-0 deficit from the first leg in Switzerland a fortnight ago.
The Swiss side’s advantage had been wiped out after just ten minutes, when ex-Chelsea winger Arjen Robben fired across visiting goalkeeper Yann Sommer after Thomas Mueller’s shot was deflected into his path.
Mueller was more fortunate after 42 minutes, volleying home from Robben’s cross.
The host’s first-half dominance was highlighted on the stroke of half-time, when Gomez tapped in Holger Badstuber’s pull-back.
Basle looked a shadow of the team that had knocked Manchester United out of this season’s tournament and the tie itself was killed off just after half time, when Franck Ribery crossed from the left for Gomez to acrobatically volley past Sommer, and the pair combined again in the 61st minute for Gomez to complete his 11th hat-trick in 18 months with a simple header.
Ribery completed his hat-trick of assists midway through the second half when he again ran riot down the left before pulling the ball back for Gomez to fire a left-footed shot into the top corner.
Robben completed the rout when he tapped in after sub Bastian Schweinsteiger’s fine through ball.
