Preheat oven to 375°F. Spray an 8x8-inch baking dish well with nonstick cooking spray.
Mix eggs. In a large bowl, whisk together 18 large eggs, 1 cup milk, 1 teaspoon salt, and 1/4 teaspoon pepper until fully combined. You can also use a blender on low speed or pulse until smooth.
Bake. Pour the egg mixture into the prepared baking dish. Bake uncovered for 10 to 15 minutes.
Stir. Remove the pan from the oven and gently stir the eggs, scraping the bottom and sides of the dish. Return to the oven.
Continue baking for 30 to 45 minutes total, stirring every 10 to 15 minutes, until the eggs are set but still soft.
Season and serve. Taste and add additional salt and pepper if needed. Serve warm.