Saturday morning, after the soup had finished cooking in the slow cooker and had had time to cool, I pureed it in a blender so that it was creamy. I should have taken a "before" picture, because the soup certainly hadn't looked at all like this. There was the pale liquid, and then the leeks, potatoes and fennel floating around as fairly unbroken pieces. I had to do it in two batches, but it wasn't as much of an ordeal as I had first anticipated. Of course, taking apart and washing all the blender bits took a little bit of work, but I still had it done fairly quickly. That begs the question: Do I need an immersion blender? I guess I'll have to think about that, although I would dearly like one.
Moocow suggested that I only puree a portion of the soup next time, to give it some texture. Having tried the soup (and finding that I probably pinched in more cayenne pepper than I had planned to), I think a little bit of texture would not be unpleasant. I think it could do with a bit more fennel flavour, though. And a bit of garlic probably wouldn't go amiss. The recipes in Beth Hensperger's "Not Your Mother's Slow Cooker Recipes for Two" could definitely do with a bit of tweaking. I wonder if I'll ever get comfortable enough with my slow cooker to skip a recipe entirely.
To serve the pureed soup, I reheated it, and then stirred in some butter and soymilk (both suggested in the original recipe, although milk can certainly substitute for the soymilk). Then, just to dress it up for its photoshoot, I put some fennel fronds on top.