May substitute 1/2 cup of broccoli for zucchini if desired.
Heat olive oil in a nonstick skillet over medium heat; cook and stir shallot and garlic in the hot oil until softened, about 5 minutes. Add zucchini; cook, stirring occasionally, until tender, about 5 minutes.
Whisk egg whites, salt, and thyme together in a small bowl; mix into zucchini mixture.
Cook, undisturbed, over low heat until frittata is set, about 2 minutes. Flip frittata and cook for 1 more minute. Season with salt and pepper.
Per Serving: 138 calories; protein 16.5g; carbohydrates 7.9g; fat 5g; sodium 635.6mg.