Blogger added an "XL" photo size, so I've changed my layout to accommodate even BIGGER close-ups of cookies. I've gone back and changed the sizes of the October pictures; older pics are still the same size, but centered so the layout isn't too wonky in older posts.
Thanks to Independent Fashion Bloggers, who have step-by-step instructions on how to do this without losing your sidebar, as I did the first time I tried it.
And if you're interested in such things, the settings that work best for me with this new picture size are:
header wrapper = 910
outer wrapper = 910
main wrapper = 660
sidebar wrapper = 220 (unchanged)