01 - Whisk together eggs, milk, salt, pepper, and Italian herbs in a medium bowl until smooth and fully combined.
02 - Stir cherry tomatoes, spinach, bell pepper, onion, zucchini, and cheese (if using) into the egg mixture until evenly distributed.
03 - Preheat the air fryer to 350°F for 3 minutes to ensure proper cooking temperature.
04 - Brush a 7-inch round, oven-safe pan or cake tin with olive oil to prevent sticking.
05 - Pour the egg and vegetable mixture into the prepared pan, spreading ingredients evenly.
06 - Place the pan in the air fryer basket and cook at 350°F for 12–15 minutes until set in the center and lightly golden on top.
07 - Let the frittata cool for 2 minutes to set, then slice into wedges and serve warm.