With sharp knife, cut zucchini lengthwise in half. With spoon, scoop out zucchini leaving 1/4-inch-thick shell. Reserve zucchini flesh.
Cook zucchini shells in microwave safe dish for about 2 minutes.
Dice reserved zucchini flesh. In microwave-safe bowl, place diced zucchini, olive or salad oil, diced tomato, garlic and thyme leaves; stir well. Cook on High 2 to 3 minutes, until tender, stirring halfway through cooking.
Into vegetable mixture, stir breadcrumbs and Parmesan. Season with salt. With spoon, mound an equal amount of vegetable mixture in each zucchini shell.
In baking dish, arrange stuffed zucchini with stem ends toward edges. Cook, covered, on High 2 to 3 minutes, until hot. Let stand, loosely covered, 2 minutes.
If you'd like to grill it, place stuffed zucchinis in a grill basket and grill for about 10 minutes.
Arrange stuffed zucchini on warmed serving platter and enjoy!