01 - Preheat oven to 375°F.
02 - Heat 1 tablespoon olive oil in a 10-inch ovenproof skillet over medium heat. Add onion and bell pepper; sauté for 3 minutes.
03 - Add zucchini; cook for 3 additional minutes until just tender.
04 - Stir in cherry tomatoes and spinach; sauté until spinach wilts, about 1 minute.
05 - In a large bowl, whisk eggs with basil, chives, salt, and pepper until well combined.
06 - Pour eggs evenly over sautéed vegetables in the skillet. Gently shake pan to distribute.
07 - Cook on stovetop over low heat for 3–4 minutes, until edges just begin to set.
08 - Drizzle remaining olive oil over the top, then transfer skillet to oven. Bake for 15–18 minutes, or until center is set and top is lightly golden.
09 - Let cool slightly, slice, and serve warm or at room temperature.