Cut top or "lid" from tomatoes, scoop out most of the pulp, and place it in sieve or colander to drain. Sauté shallots and garlic in butter for about 1 minute. Add zucchini, tomato paste, basil and reserved tomato pulp; raise heat and cook, stirring constantly, for two more minutes or until filling is thickened and watery liquid is evaporated. Season with salt and freshly ground black pepper. Spoon filling into tomato shells and sprinkle 1 tsp grated parmesan cheese over each. Wrap in single thickness heavy-duty aluminum foil, or double thickness of regular foil. May be refrigerated at this point. Barbecue over very hot coals (or in 450-500 F oven) until tomatoes are soft, cheese is melted, and filling is heated through (about 15 minutes). Garnish with whole fresh basil leaves. Serves 6.
Thanks to Bessie Nidell.