3. Peel the onions; cut them in half, then into very thin slices, adding to the skillet. Once they're all in, stir until they've started to brown. Sprinkle with salt, then cook the onions for about 30 minutes, stirring a few times, until they are soft and browned. Transfer to a bowl.
4. Add a generous pinch of salt to the pot of water, then add the pasta. Cook to the package directions. Drain, reserving 1/2 cup of the pasta water; return to the pot (off the heat).
5. While the pasta and onions are cooking, melt the butter in a small skillet just until it browns (5 to 7 minutes). Pour into the pasta and stir to coat, then stir in the yogurt. If the mixture seems too thick, add some of the pasta water. Cover to keep warm.
6. Divide the pasta among individual plates. Sprinkle with equal amounts of the grated cheese, then top with equal amounts of the browned onions and their juices. Serve hot.
- Adapted from The Country Cooking of Greece (Chronicle, 2012).
Per serving: 540 calories, 24 g protein, 61 g carbohydrates, 23 g fat, 14 g saturated fat, 55 mg cholesterol, 230 mg sodium, 4 g dietary fiber, 13 g sugar