Preheat the oven to 375°F
Whisk eggs with salt and pepper
Add milk or cream if desired
Heat an oven-safe skillet over medium heat
Add oil or butter to the skillet
Cook chopped vegetables until tender
Add cooked meat or other fillings if using
Pour the egg mixture into the skillet
Stir gently to distribute the fillings
Cook on the stovetop until the edges start to set
Transfer the skillet to the oven
Bake until the center is set
Remove from the oven
Let rest for a few minutes
Slice and serve