Preheat your oven to 400 degree F. Start by sautéing the vegetables. Put a little oil in a skillet and cook the vegetables on medium heat. First sauté the onions till they becomes soft and translucent, you can caramelize it a little if you prefer. Add the bell pepper and cook for another minute. Add in the shredded chicken so that it gets warm. As the vegetables will be added to the eggs, you need to season them more to bring out the taste. Add your choice of seasoning or use mixed herbs. Sprinkle half a teaspoon of salt. Let the mixture cook for a minute, taste and make adjustments accordingly. You can add more red peppers if you want it spicy.
Take the mixture and spread it in a layer at the bottom of the pan. The mixture should still be warm when you transfer it. Top it with shredded cheese and let the cheese melt a little with the heat of the warm mixture. In a separate bowl, break eggs one by one and whisk them. Pour the raw eggs over the cheese and vegetables. Tilt the pan on both sides so that the base is fully coated. Cook it for around 2 to 3 minutes. You will notice that the sides will begin to set.
Now it’s time to bake the frittata. Put the pan in the preheated oven and let it bake for 9 to 10 minutes. The eggs will set by then. Check if it is done by making a slit in the middle of the frittata. If the egg is still liquidy and runs in the cut, then it is not done yet. Bake for a few minutes more. Check again, if it is done and take it out. Let it cool for at least five minutes before slicing it. Serve it warm. If you have any leftovers, they can be eaten for up to a week if kept in a refrigerator.