Rub peppers with 1 tablespoon oil and place, cut side down, on foil-lined baking sheet. Broil until skin starts to blacken, 8 to 10 minutes. Immediately transfer to bowl; cover with plastic wrap and let sit until tender, 12 minutes. Remove and discard skin.
In a food processor, pulse walnuts, lemon juice, garlic, sumac, cayenne, remaining tablespoon of olive oil and ½ teaspoon salt to combine. Pulse in peppers until mostly smooth but still a bit chunky. Stir in bread crumbs.
Transfer to serving bowl. Drizzle with oil and pomegranate molasses, if using, and sprinkle with more walnuts.
