Heat oven to either broil on hi if using traditional stove top method or pre-heat to 375-degree F. to bake in oven.
Add eggs, cream or milk, mustard, a dash of salt/pepper to a large mixing bowl with cream or milk. Whisk until blended. Add in the cheese and whisk once more. Set aside.
Heat an iron cast over medium heat. Add oil. Always start with onions (unless using bacon or sausage-cook first then set aside then proceed) to saute for 2-3 minutes. Add in vegetables that take longer to cook and saute 2-3 minutes. Add in thinner vegetables such as squash/tomatoes. Cook until vegetables are tender. Add in garlic and any kind of greens if using (spinach, kale, arugula) until wilted. Season with salt to taste. Add in dried spices if using.
Pour the egg mixture over the vegetables and add reserved cheese if desired.
Stovetop method: turn the heat to low and let the eggs set till an outer shell forms. Use a baking spatula to rub between the pan and the eggs to help form the shell and tilt the pan as it cooks to even out the filling to ensure even cooking. Finish in the oven on broil and watch closely.
Oven method: Bake it in the oven for 12 minutes or until the eggs set. Can finish on a quick 1-2 minute broil if desired.
