Eggs with Red Onion and Fresh Spinach

This is a scrambled egg dish I made throwing some
fresh spinach and sliced red onion into the pan,
it came out good and tasty.

Ingredients:
1 1/2 tablespoons unsalted butter
10 eggs
2 tablespoons milk or water
1 teaspoon salt or to taste
1/4 teaspoon freshly ground black pepper
1 thinly sliced medium red onion
5-ounce bag of prewashed baby spinach

Directions:
Heat butter in a large nonstick skillet over medium heat.
Add onion and sauté until softened.
Meanwhile, in a large bowl, whisk together the eggs,
milk, 1 teaspoon kosher salt, and 1/4 teaspoon pepper.
Pour into the pan and cook, stirring occasionally,
to desired doneness, 4 to 5 minutes,
adding spinach just before the eggs are set.