• Preheat the oven to 350°F (180°C).
• Crack an egg into a small bowl, check if it is good, and then add it into a medium bowl. Repeat for all the eggs.
• Add the milk and whisk until the egg yolks and whites are blended. Add the cheese, and season with salt and pepper. Set aside.
• In a 12-inch (30cm) cast iron skillet (or any other large skillet), warm the olive oil over medium heat until lightly shimmering. Add the chopped spring onions (the white part) and stir until softened. Proceed with the peppers and the mushrooms. Cook for a few minutes, stirring occasionally, until the vegetables are tender enough. Season with salt, to taste.

Instructions for baking dish/casserole

• Lightly grease a 9x13-inch (23x33cm) baking dish with olive oil. Evenly spread the cooked vegetables across the bottom of the dish. Pour the egg, milk, and cheese mixture over the vegetables, then gently shake the dish to ensure the mixture is evenly distributed.
• Arrange the tomato or cherry tomato slices on top (optional). Place the baking dish on the middle rack of a preheated oven at 350°F (180°C) and bake for approximately 20 minutes, or until the center is set.
• To check for doneness, insert a knife into the center. If it comes out clean, remove the dish from the oven. Garnish with sliced spring onion greens or your preferred herbs before serving.

Instructions for oven-safe skillet

• Pour the egg-milk-cheese mixture over the cooked vegetables into the skillet. Shake gently to distribute the mixture evenly across the pan.
• Top with the tomato or cherry tomato slices (optional). Bake at 425°F (200°C) for 10 to 15 minutes, until set in the center. Use a knife to check the center and if it comes out clean remove the skillet from the oven. Garnish with spring onions (the green part) or the herb of your choice.