Whisk the eggs in a large mixing bowl. Add the ham, cheese, parsley, chives, salt and pepper and mix.
Preheat the bottom pan of the 10-in. nonstick frittata pan over medium heat. When the rim of the pan is hot to the touch, add the butter. When melted, add the mushrooms and sauté for 3 - 4 minutes.
Add the egg mixture and attach top frittata pan to cover eggs. Reduce heat to low. Cook the egg mixture until the eggs just begin to set over the entire surface, about 10 - 12 minutes.
Using an oven mitt, carefully hold the two handles of the frittata pans together and flip the pan. Cook the frittata on the other side for about 7 - 10 minutes or until golden brown.
Slide the frittata loose onto a warmed serving plate. Delicious served with crispy fried potatoes.