Preheat the oven to 350°.
Line a 13 x 18 sheet pan with foil and spray with nonstick cooking spray. Using a bigger or smaller pan may affect the cook time.
In a large bowl, whisk together the eggs, half and half, garlic powder, onion powder, and salt and pepper to taste, until well combined.
Pour the eggs into the prepared baking sheet.
Sprinkle the vegetables evenly over the eggs.
Sprinkle the cheese evenly over the eggs.
Bake for 20-25 minutes, until the eggs are set, the cheese is melted, and vegetables are soft.
Let cool for 2 minutes, then cut into servings with a pizza cutter.