I like the idea. In fact, I have been thinking of something similar. But I would like it to be more cooking-related, including recipes along.
One way for that would be to ask people to submit both a picture of their food and the recipe they used. Then the selected picture will go to the banner, and link to the meta-thread with the recipe in it. But I am open to any other idea which brings a more culinary twist to the thing.
Another thing to think of is if it won't be a nice promotion if the topic is announced in advance, so we can have a pie picture while the pie contest is running. However, this is somewhat problematic, because people seem to prefer to make the contest items during contest, hoping to come up with good questions. Doing this one week beforehand would require them to remember the question for a week, which is suboptimal. So maybe the week-after is the better time; I would like to hear other opinions about that.