In a bowl mix in a splash of milk together with 3 eggs. Beat your eggs and milk mixture and add a pinch of salt and set it aside. Heat up a pan and pour in some cooking oil. Add in 1 chopped onion into the pan. Make sure the heat is on medium low. Let the onion sauté for 2 minutes then add in a cup full of chopped spinach. Cook it until the water has evaporated. Dice two garlic cloves and add into the spinach. Stir and let it cook for a few minutes. Sprinkle some salt and chili flakes. Pour in your eggs into the spinach. As the eggs are forming a base; preheat your oven to 350 degrees C. Once the base is formed sprinkle a handful of cheddar cheese on top. Put your pan into the oven for a few minutes and once the cheese is melted and golden brown. Let it cool for a bit the serve.
NOTE; Spinach frittata is really good for breakfast.