Cook pasta according to package directions, omitting salt. Drain and rinse; set aside.
Cuttops from tomatoes; scoop out and discard all but 1/2 cup tomato pulp. Chop tomato pulp; add to pasta. Place tomatoes, cut-side down, on paper towels; let drain 5 minutes.
Preheat oven to 350 degrees. Place basil and garlic in blender or food processor; process until finely chopped. Add mayonnaise, milk and black pepper; process until smooth.
Combine pasta mixture, zucchini and basil mixture; toss to coat evenly. Place tomatoes, cut-side up, in 8-inch bakingdish. Divide pasta mixture evenly among tomatoes, mounding filling slightly; sprinkle with cheese. Bake 10 to 15 minutes or until heated through.