Combine soup, milk, salt, chicken, vegetables, half of the cheese and half of the onions. Place in 12 x 8-inch baking dish. Cover and bake at 375° for 20 minutes. Unroll crescent dough and separate into 2 pieces, pressing perforations to make two large rectangles. Cut each rectangle lengthwise into 3 or 4 strips. Place strips onto hot casserole to form a lattice top. Bake, uncovered, 15 minutes more. Top lattice with remaining cheese and onions; bake, uncovered, 3 to 5 minutes more, until onions are golden brown. Makes 4 to 6 servings.