How to Make It
In a bowl, whisk the eggs, water, salt and pepper. Stir in the cheese.
In a medium nonstick skillet, heat 3 tablespoons of the olive oil. Add the zucchini; cook over moderately low heat until just softened, 5 minutes. Add the garlic and cook, stirring, for 2 minutes. Let cool; then stir into the egg mixture.
Preheat the broiler. In the skillet, heat the remaining 2 tablespoons of oil over moderate heat. Add the egg mixture, cover, reduce the heat to low and cook until firm, about 5 minutes. Uncover and broil for 2 minutes, or until golden brown.
Slide the frittata onto a serving plate and sprinkle with the thyme. Serve at room temperature.