01 - Preheat the oven to 375°F.
02 - Heat olive oil in an oven-safe nonstick skillet over medium heat.
03 - Add diced pancetta and cook for 3–4 minutes until golden and crisp. Remove pancetta from pan and set aside, leaving the rendered fat in the skillet.
04 - Add chopped onion and sliced zucchini to the pan. Sauté for 5–7 minutes until soft and lightly golden.
05 - In a large bowl, whisk together eggs, milk, Parmesan, salt, and pepper. Stir in chopped parsley and chives until well combined.
06 - Return cooked pancetta to the skillet, spreading it evenly with the sautéed vegetables.
07 - Pour the egg mixture over the vegetables and pancetta, gently stirring to distribute all ingredients evenly throughout the pan.
08 - Cook on the stove over medium heat for 2–3 minutes until the edges begin to set.
09 - Transfer skillet to the preheated oven and bake for 10–12 minutes, or until the frittata is fully set in the center and lightly golden on top.
10 - Remove from oven and let rest for 2 minutes before slicing. Serve warm or at room temperature.