Core 2 large heads cauliflower and cut into 1/2-inch-thick "steaks." Cook in a steamer basket over boiling water, covered, until tender, 30 to 40 minutes. Transfer to a large bowl and let cool 15 minutes. Whisk 1 teaspoon grated lemon zest, 1/3 cup each lemon juice and olive oil and 2 1/2 teaspoons kosher salt; drizzle over the cauliflower and toss. (The cauliflower will break apart.) Let stand 10 minutes. Add 1 cup fresh parsley, 1/2 cup toasted pine nuts and 2 ounces shaved Parmesan; toss. Drizzle with olive oil.