Hard-Boiled Egg Yolks
Place the entire egg in a saucepan.
Pour cold water into the saucepan until the water is about 1 inch over the top of the egg. Cover and bring to a boil.
Reduce heat to a slow boil, and cook for an additional 12–14 minutes. Once done, drain the hot water and fill the saucepan with cold water to stop the egg from cooking. Let cool for 10–15 minutes.
Tap the egg lightly; then peel the shell off. Cut the egg in half and remove the white.
Mash the egg yolk with a fork. Add breastmilk or formula, 1 tablespoon at a time, until the egg is a creamy texture.