In a large bowl, combine first 11 ingredients and 1 can of the tomato sauce; mix well. Stir in tomatoes. Halve zucchini lengthwise; scoop out seeds. Fill with meat mixture; place in two 13x9-in. baking dishes. Spoon remaining tomato sauce over each.
Bake, uncovered, at 375° until the zucchini is tender, about 45 minutes. Sprinkle with cheese during the last few minutes of baking.
To make soft bread crumbs, tear bread into pieces and place in a food processor or blender. Cover and pulse until crumbs form. One slice of bread yields 1/2 to 3/4 cup crumbs. Wear disposable gloves when cutting hot peppers; the oils can burn skin. Avoid touching your face.