When confronted with multiple pounds of beets from my CSA, I tried to think of something to do that wasn’t a beet salad or a roasted-beet sandwich. I made some pickled beets, but I only needed so many of those. What to do with the rest? The answer lay in the other things I had on hand, which included a big chunk of Parmesan cheese and a couple of fennel bulbs (also from my CSA). I use fennel and Parmesan when I make potato gratin, so I thought, why not do a gratin with another root vegetable? 

You’ll want to use a mandoline to slice the fennel bulbs and beets nice and thin (and with even thickness), but be really careful because the roasted beets can be pretty slippery. I suggest serving this with some simple steak or roast chicken, something hearty to go with the earthiness of the beets, but nothing too crazy, as the gratin is pretty rich.