Heat oven to 375°F.
Heat 2 tbsp olive oil in a 10-inch non-stick skillet over medium-high heat.
Add onion and zucchini to skillet and sauté till golden and softened.
Meanwhile, beat eggs in a large bowl. Add a splash of water (about 1-2 tbsp), and season with salt and pepper. Remove leaves from thyme and add them to the bowl.
Cut cheese into small cubes and add to eggs.
When onion and zucchini are done, add to bowl with eggs. Mix well and let stand for 10 minutes.
Heat remaining tbsp of olive oil in now empty skillet over medium heat. Add egg mixture and cook until eggs just begin to set on the bottom.
Place in oven and cook for 10-15 minutes, until golden brown and puffed. Carefully remove from oven, keeping a towel over handle. It should slide right out of the pan onto your cutting board.
Serve with a salad for a complete light dinner.