Chard and Sweet Potato Gratin (or winter squash)

I am a bit late to the party for Smitten Kitchen, but smarter heads prevailed in a recent search for delicious vegetarian dish that would use up some of the chard that is (still!) growing in the garden. The recipe for swiss chard and sweet potato gratin at Smitten Kitchen turns out a delicious crowd-pleaser that I've made twice so far (and will definitely make again!).

The first time around, we had some winter squash puree that we'd frozen amidst the squash deluge from the CSA this fall, so we substituted squash for the sweet potatoes. It was delicious.

Then for Thanksgiving we followed the recipe more closely, using sweet potato rounds and an applewood smoked gruyere that imparted this dish with an almost bacon-y scent and taste. Everyone (well, almost everyone) at Thanksgiving dinner gave the dish a thumbs up. (A couple folks swore up and down that they don't like sweet potatoes. I don't know how it is that I am related to them.)

Finally, a friend of mine also made this dish for a fall potluck. Instead of chard, she substituted frozen mustard greens, and she kept the sweet potatoes. It was a hit.