Step 1

Preheat oven to 400 degrees F.

Step 2

In a large bowl, whisk together eggs, milk, salt, and pepper until foamy.

Step 3

Melt butter in a cast-iron pan over medium heat. Add the onion and potatoes and cook thoroughly. Pour the eggs over the mixture.

Step 4

Pull the edges away from the sides of the pan with a spatula so the eggs flow to the bottom of the pan. When the frittata is half set, add the ham.

Step 5

Transfer the pan to the heated oven. Bake for 10 minutes until puffed and golden. Top with sour cream, salsa, and chives before serving.