Preheat oven to 350 degrees F. Melt butter in a microwave safe bowl or place it in a 9x13 pan in the oven as it preheats to melt it that way while you prepare the eggs.
In a large bowl, crack all of the eggs and whisk well. Pour in the milk and salt. I use a fine sea salt so if you are using something other than that you may need to add more after the eggs have cooked. Add pepper if desired.
Pour melted butter in a 9x13 pan (or if it's already melted in the oven just continue). Pour eggs in baking dish.
Bake for 10 minutes then stir well pushing the outside edges in as they cook faster. Bake for another 10-20 minutes until set, fluffy with a spoon. They might need a bit longer depending on your oven.
Options: Add diced onion, peppers, ham, or bacon in the mix. You can also sprinkle your favorite cheese on top for the last 5 minutes.
Notes
Source: Jill Porter. I reduced the milk and salt just a little.