What was found
CREW OBSERVED SMOKE ENTERING COCKPIT WHILE IN CRUISE. 1ST CLASS OVENS WERE IN USE. FLT ATTENDANT TURNED OFF 1ST CLASS OVENS & SMOKE CEASED. FLT CONTINUED & LANDED WITHOUT FURTHER PROBLEM. VISUAL INSPECTION PERFORMED BEHIND OVENS, COFFEEMAKER, & P-6 PANELS, NO DEFECTS NOTED. BOTH 1ST CLASS OVENS R & R AS A PRECAUTION IAW MM 25-34-34. OPS CHKS GOOD, NO SMOKE NOTED. PREVIOUS FLT EXPERIENCED SMOKE IN COCKPIT/CABIN & SOURCE DETERMINED TO BE A BURNED LOAF OF BREAD WRAPPED IN A PLASTIC BAG INSIDE FWD GALLEY OVEN. TEARDOWN REPORTS FOUND NO FAULT WITH ONE OVEN. SMOKE A RESULT OF BURNING RESIDUE IN OVERHEATED OVEN.