I followed the recipe I developed HERE adding 1 package of cooked frozen spinach (squeezed dry in a towel), a quick shake of garlic powder and 1/2 cup grated Parmesan cheese. I added them to the sponge along with the honey and salt before working in the rest of the flour. I also substituted 2 cups of all-purpose flour for part of the bread flour. I'm not sure that was a good idea, but we'll see tomorrow when I bake them. Stay tuned.
It worked! If I make these again, I'd stick to using all bread flour, but otherwise-spinach bagels are a new recipe to add to my collection. Cool.