Westjet does not currently have ovens on their Boeing 737s, but the two Thomas Cook aircraft currently being leased by Westjet for the YYC/YEG-Hawaii flights do have ovens and hot food items such as mac and cheese can be prepurchased online or purchased on board on a first come first serve basis. I think this might be serving as a trial for future hot food item purchases on mainline (767 perhaps, maybe 737 but not sure how that would work unless they can be pre cooked and left in a warming cart???).