Preheat oven and grease muffin tin: Preheat the oven to the specified temperature and grease a muffin tin to prevent sticking.
Beat eggs: Crack eggs into a bowl and beat them until well-combined.
Add ingredients: Mix in desired ingredients such as diced vegetables, cooked meat, cheese, and seasonings.
Pour into muffin tin: Distribute the egg mixture evenly among the muffin cups.
Bake: Place the muffin tin in the oven and bake until the eggs are set and the tops are lightly golden.
Serve or store: Allow the egg muffin cups to cool slightly before serving, or store them in an airtight container for later enjoyment.