Preheat oven to 350°. Cut each zucchini lengthwise in half. Scoop out pulp, leaving a 1/4-in. shell; chop pulp. Place zucchini shells in a large microwave-safe dish. In batches, microwave, covered, on high 2-3 minutes or until crisp-tender.

In a large skillet, cook sausage and zucchini pulp over medium heat 6-8 minutes or until sausage is no longer pink, breaking sausage into crumbles; drain. Stir in tomatoes, bread crumbs, Parmesan cheese, herbs and pepper. Spoon into zucchini shells.

Place in two ungreased 13x9-in. baking dishes. Bake, covered, 15-20 minutes or until zucchini is tender. Sprinkle with mozzarella cheese. Bake, uncovered, 5-8 minutes longer or until cheese is melted.