Chop broccoli into florets and remove stem. In a large pot, fill halfway with water and bring to a boil. Prepare 2 ice baths.
Boil broccoli for about 4 to 5 minutes until fork tender. Transfer broccoli to the ice bath but leave water remaining.
Add the spinach, blanch for 30 seconds, then remove and place into the other ice bath. Set aside.
Drain water from the pot. Heat olive oil over medium heat and sauté shallots and garlic for about 3-4 minutes.
Add the za'atar and sauté until fragrant, about 1 minute.
Add broccoli and spinach, then toss to combine.
Add the silken tofu, preserved lemon, lemon juice, lemon zest, and red pepper flakes to the pot and blend until combined using an immersion blender (or transfer to a blender if preferred).
Boil pasta in salted water until just under al-dente. Drain pasta and reserve 1 cup pasta water.
Add about ¾ cup sauce to the pasta with about ⅓ cup of reserved pasta liquid. Stir until combined.
Taste and adjust seasoning, adding more salt or lemon juice/zest if more brightness is desired.
Plate and garnish with parmigiano reggiano, lemon zest, and fresh chopped parsley.
