Crack 4 large eggs into a bowl; add 2 tablespoons milk and 1/4 teaspoon salt. Whisk until the mixture is smooth and slightly frothy.

If the 1 large ripe avocado is not already prepared, pit and peel it, then chop into 1/2-inch cubes; set the avocado aside.

Place a nonstick skillet over medium-low heat. Add 1 tablespoon unsalted butter and let it melt, tilting the pan to coat the surface evenly.

Pour the egg mixture into the skillet. Let it sit undisturbed for about 10–15 seconds, then gently stir and fold the eggs with a spatula, scraping the bottom and sides.

When the eggs are about halfway set but still soft and slightly runny, add the avocado cubes and continue to cook, stirring gently, until the eggs are soft, fluffy, and no visible liquid egg remains.

Remove the skillet from the heat. Season with freshly ground pepper to taste, gently fold once to distribute, and transfer the eggs to plates.

Sprinkle 1 teaspoon chopped chives over the eggs if desired, and serve immediately.