Pasta With Creamy Yogurt Herb Sauce

Preparation:

1. Heat a large skillet (about 12") over medium high heat. When the pan is hot, add a tablespoon of olive oil. Add the kale and toss until coasted with oil and staring to brown.
2. Add 1/4 cup of water, cover and cook until kale is bright green and softened. Remove kale from pan and add another swirl of olive oil.
3. Add the zucchini and onion along with a pinch of salt. Saute over medium heat until onion is softened and starting to brown. Add chili flakes. Set aside.
4. While zucchini and onion are cooking, bring a pot of salted water to a boil and cook spaghetti until just al dente (follow directions on package).
5. Drain (but do not rinse!) pasta. The starch from the pasta cooking water will help your sauce stick to the noodles. Reserve pasta water.
6. Meanwhile, toast walnuts in a dry skillet over medium low heat. Monitor closely and remove from heat once the nuts are beginning to brown and releasing their oils. Let cool slightly and chop coarsely.
7. In a large bowl, mix the yogurt, herbs, lemon zest and juice, and garlic. Season with salt and pepper to taste. Add 1/2 cup pasta water along with the hot pasta and toss with tongs. The sauce should be thick and glossy. Add kale, zucchini, walnuts and Parmesan. Add a little more pasta water if needed to loosen the sauce.
8. Swirl pasta into bowls and sprinkle with more Parmesan.