- Bring cauliflower florets, milk, and shallot to a simmer in large saucepan. Reduce heat to low. Cover pan, and cook 15 to 17 minutes, or until cauliflower is very soft. Transfer contents of pan to blender. Blend until silky smooth, adding 1 or 2 more Tbs. milk, if necessary. Transfer purée to small bowl, and whisk in yogurt. Season with salt and pepper, if desired.
- Meanwhile, cook linguine in large pot of boiling salted water 10 to 11 minutes, or until al dente. Drain pasta, reserving 1 cup pasta water.
- Melt butter in same pot over medium heat. Add whole kale leaves, and toss 2 minutes, or until wilted but still bright green. Add pasta, 11/4 cups cauliflower purée, 2/3 cup Parmesan, lemon zest, and nutmeg. Toss until sauce coats pasta, adding reserved pasta water by 1/4 cupfuls if dry. Season with salt and pepper, if desired. Serve sprinkled with reserved chopped kale and remaining 1/3 cup Parmesan.