Place the eggs in a saucepan. Use a pan large enough for the eggs to sit in a single layer. Pour cold water over the eggs until they are fully covered, with about 2–3 cm of water above them. Set the pan over medium-high heat. Bring the water to a boil. Let the eggs simmer gently for 9–10 minutes (for hard-boiled eggs). Once cooked, drain the hot water. Rinse the eggs under cold running water. Let them cool completely. Peel the eggs and chop them into small pieces.