Air Canada flight 1038, a scheduled international passenger flight from Denver International Airport (DEN), Denver, Colorado, to Toronto Pearson International Airport (YYZ), Mississauga, Ontario, Canada, experienced smoke and an electrical odor in the cabin, resulting in an air turnback. After landing, an evacuation was initiated, and one passenger sustained a serious injury. According to the flight crew, during climb out, the flight attendants (FAs) informed them of an electrical burning odor in the aft cabin. The flight crew turned the power to the aft galley off, but the FAs stated the odor was getting stronger and that they observed haze in the cabin. At that time, the flight crew declared an emergency and coordinated with air traffic control for a return to DEN. After landing, the flight crew stopped the aircraft on the runway and contacted the flight attendants to get an update on the situation in the cabin. The FAs stated that the situation was worse and that passengers were experiencing eye irritation. At that time, the captain commanded an evacuation. During the evacuation, FAs observed passengers standing on both wings. One FA exited onto each wing and assisted with the overwing evacuations. A passenger sustained a serious injury to their right ankle and was unable to move away from the slide. At that time, passengers were redirected into the cabin and out the left overwing exit. The remainder of the evacuation was uneventful. Post-event evaluation revealed burned debris on the baffle plate, carriers, and tray installed in an aft galley oven.