From America's Test Kitchen Season 1: Cooking Eggs
Whether eaten plain or quartered in a salad, hard-cooked eggs should have a creamy yolk, tender white, and no unsightly green ring.
It is important to start the eggs in cold water and then bring it to a boil. The eggs will heat along with the water, allowing their interior and exterior to cook at roughly the same rate. Covering the eggs with an inch of water further ensures even cooking. When the water first began to boil, we removed the pot from the heat, covered it, and let it sit for 10 minutes. Cooks debate about the ideal length of resting time, but we found that this produced consistently good results.
After the eggs were done resting, we plunged them into a bowl of ice water, which halts the cooking process and prevents a green ring from forming around the yolk. This recipe can be doubled or tripled; just be sure to use a pot large enough to hold the eggs in a single layer with a full inch of water above them.
Makes 6 eggs
You may double or triple this recipe as long as you use a pot large enough to hold the eggs in a single layer, covered by an inch of water.