Precooking the cauliflower and breadcrumbs means they will get toasty and crisp as the pie bakes. An extra step, yes, but well worth it.
- Preheat oven to 400°. Toss cauliflower, lemon, anchovies, garlic, and capers with oil on a large rimmed baking sheet; season with salt and pepper.
- Roast, tossing occasionally, until cauliflower is tender but not browned, about 20 minutes. Squeeze lemon juice over cauliflower and toss to coat. Discard lemon and garlic, if desired.
- DO AHEAD: Precooking the cauliflower and breadcrumbs means they will get toasty and crisp as the pie bakes. An extra step, yes, but well worth it.
- Meanwhile, toss breadcrumbs and oil on a large rimmed baking sheet; toast, tossing occasionally, until golden brown, 6–8 minutes. Let cool; toss with Parmesan.
- Place a rack in lower third of oven and preheat to 525° or as high as oven will go.
- Once dough has risen in baking sheet, top with mozzarella, dot with ricotta, and top with cauliflower mixture. Bake until golden brown and crisp on bottom and sides, 20–30 minutes. Top pie with toasted breadcrumbs and bake 1 minute longer.
- Serve topped with parsley.