Adapted from this recipe at 101 Cookbooks. Obviously I didn't bake it, and as always I made various substitutions and additions and removals. The natural yoghurt we bought was quite sweet, which gave the final dish an odd taste, but not one that was unlikeable. I'd like to use ricotta rather than feta (not that I used feta today!), cream cheese in the sauce, and probably spinach too. Breadcrumbs on top would be good if you were baking the pasta.
2 sweet potatoes
4 handfuls of pasta (I used conchiglie)
1 handful of chard
1/2 an onion
2 one-serving-sized yoghurts
1 egg and 1 egg yolk
Italian herb mix
I peeled the potatoes and cut them into bite-sized chunks before boiling in salted water with the pasta. Meanwhile, I fried the onions till slightly softened (they were still a little bit crunchy, which I liked) in a separate pot, and added the yoghurts, egg, and egg yolk along with a big squeeze of lemon juice and liberal sprinklings of the seasonings. Stirred the sauce until it went velvety and had heated through. Once the pasta and potatoes were almost cooked I chopped the chard and added it to the pan for a few minutes. Drained the pasta-potato-chard mix and poured it into the sauce pan. Mixed and served.