كتب : Mohamed Sabe
Claudio Pizarro, Roque Santa Cruz Bastian Schweinsteiger and substitute and Hasan Salihamidzic scored after the interval to give Bayern their first three points of the group.
Peruvian international Pizarro opened Bayern's account when he latched on to a long pass from Willy Sagnol and fired home past Spartak's keeper in the 48th minute.
Santa Cruz doubled the lead four minutes later after being set up with new-signing Mark van Bommel.
Schweinsteiger added the third in the 71st minute and Salihamidzic finished off a Lukas Podolski shot to complete the rout for the German champions.
Elsewhere, Sporting Lisbon grabbed three precious points after edging out Inter Milan for a 1-0 home win.
Marco Caneira fired home the winner for Sporting in the 64th minute, putting his side in second place with three points, trailing Bayern on goal difference.