Brush a rimmed sheet pan with olive oil, then lay the zucchini out in an even layer.
Brush zucchini with more oil and sprinkle generously with salt.
Broil until golden brown, about 5 minutes.
Flip and broil until golden in spots, 4 to 6 minutes.
Meanwhile, in a small bowl, toss together bread crumbs, Parmesan, anchovies, garlic, Herbes de Provence, red-pepper flakes and 1/4 teaspoon salt.
Add 2 tablespoons oil and use your fingers to rub oil, garlic and anchovies into the crumbs.
When zucchini is browned on both sides, turn off broiler and set oven to 500°F.
Sprinkle zucchini with mozzarella, then bread crumb mixture; generously drizzle with oil.
Bake until cheese melts and bread crumbs turn golden, about 4 minutes.
Grind black pepper over top and drizzle with more oil, if needed.
Top zucchini with olives, basil or parsley and additional red-pepper flakes, if desired, and serve with lemon wedges for squeezing.
