Preheat oven to 350° F.
Wash the zucchini and trim off the ends. Cut zucchini in half lengthwise and scoop out the seeds. Be sure to leave some by the ends to create a boat-like shape.
Sauté onions in butter until clear, add tomatoes and simmer until soft.
In a mixing bowl combine tomato and onion mixture, shrimp, basil, salt and pepper and half of the bread crumbs. Fill the zucchini boats with the mixture. Place boats in a greased baking dish. Sprinkle with remaining breadcrumbs and drizzle with butter. Bake for 15 minutes or until shrimp are pink and clear.
Makes: 8