Preheat oven to 350°F. Heat oil in large cast iron skillet over medium heat. Add zucchini; cook about 2 minutes or until crisp-tender, stirring frequently. Add tomatoes; cook 1 minute, stirring frequently. Remove zucchini mixture from skillet. Wipe skillet clean; generously spray with nonstick cooking spray.
Whisk eggs and half-and-half in medium bowl until well combined; stir in 1 cup cheese, thyme, salt and pepper. Pour egg mixture into prepared skillet; spread zucchini mixture and sausage evenly on top as desired.
Bake 20 to 25 minutes or until egg mixture is set. Sprinkle with remaining ¼ cup cheese; bake about 3 minutes or until knife inserted near center comes out clean. Let stand 5 minutes before serving. Garnish with thyme.