Cut squash in half lengthwise; remove seeds. Place squash halves cut sides down in a baking dish. Bake in a 350 degree F oven for 30 to 40 minutes or until tender. Or place halves cut side down in a microwave safe baking dish with 1/4 cup water. Microwave, covered, on 100 percent power (high) 17 to 20 minutes or until tender rearranging once.
Using a fork, scrape squash making long shreds. (You should have about 2 cups cooked squash.) Place squash in a mixing bowl; stir in salad dressing. Cut off tops of cherry tomatoes. Use a small spoon to hollow out tomatoes. Fill centers with cooked spaghetti squash. Place a pimiento -stuffed olive in the center of the squash mixture in each tomato. Cover and chill up to 4 hours before serving. Makes 24 servings.