Preheat the oven to 375 degrees. Thoroughly coat a skillet with butter (preferably a cast iron or oven proof skillet).
Whisk eggs and half & half together in a bowl. When whisking, try to incorporate as much air as possible by gently lifting the whisk as you stir.
Add the half of the shredded cheese, seasoning salt, and pepper to the egg mixture (reserve remaining cheese for topping). Pour the mixture into your skillet.
After all desired veggies are chopped into bite size pieces, add them directly to the skillet with the egg mixture. Try to separate them to ensure even distribution.
Top with remaining cheese. Place it in the oven and bake for approximately 15 minutes
Notes
Frittata will come out of the oven super fluffy, and then it will flatten out (or cave in a bit). This is normal due to the heat/oxygen expansion that occurs in the oven. Keep an eye on the frittata, as it may need to come out sooner than 15 minutes depending on oven settings.Check notes in the post for different addition ideas. Get creative!