Halve the zucchini, hollow out and briefly blanch in lightly salted water. Dice tomatoes, onions and boiled ham, add to the cream cheese and stir to a smooth mass while adding milk. Season to taste with salt and pepper. Place the zucchini halves in a baking dish, fill with the cream cheese mixture and sprinkle with cheese. Baked at 180-200 degrees until the cheese has melted golden yellow.