Whisk the eggs together and add the salt and pepper. Remove the skillet of from the stovetop. Pour the egg mixture over the vegetables, stirring gently to evenly distributed the zucchini in the pan. Place the skillet in the oven. Bake the frittata for about 10-12 minutes, uncovered. Cook until the eggs are almost set. Sprinkle on the ?cheese and bake for another 5 minutes, or until the frittata starts to turn lightly golden in color. Remove the skillet from the oven and let it cool for a few minutes. Cut the frittata into wedges, sprinkle on the fresh chives and serve. You can let it cool and serve it at room temperature. The frittata can be made up to 2 hours in advance.