Addendum: Reader Jenny Alworthy has added information to this post in her comment which makes absolute sense:
I think what this illustration shows is that because many people didn't have room in their oven to cook their dinner, they prepared it in advance and then took it to the baker's (who had a huge oven) just to get it cooked. I imagine they would pay the baker a small sum for the use of their ovens. I don't think that the baker actually prepared the food for them.Have a safe and happy holiday this season, as this blog reduces the number of posts for the time being.Thank you all for visiting! Vic, Tony, and Raquel.