Preheat your oven to 375°F if using an oven-safe skillet.
In a mixing bowl, whisk together the eggs, salt, and pepper until well combined. Set aside.
Heat the olive oil in a skillet over medium heat. Add the chopped onion and sauté for about 2 minutes until softened.
Add the diced zucchini to the skillet and cook for another 3-4 minutes, until slightly tender.
Stir in the halved cherry tomatoes and cook for an additional 2 minutes.
Pour the egg mixture into the skillet over the sautéed vegetables. Gently stir to combine.
Cook for about 5 minutes on the stovetop, just until the edges start to set.
If using an oven-safe skillet, transfer it to the preheated oven and bake for about 10 minutes, or until the center is set and the top is slightly golden. If not using an oven, cover the skillet with a lid and cook until the eggs are fully set.
Remove from heat and let it cool for a few minutes before slicing.
Garnish with fresh basil or parsley, if desired, and serve warm.