Preheat oven to 350℉. Grease a 2-quart baking dish.
In a mixing bowl, whisk together the eggs, milk or cream, salt, and pepper until smooth and well combined.
Pour the egg mixture into the prepared baking dish. Scatter the butter pieces over the top.
Bake for 20 minutes. Remove from the oven and stir. Return to the oven for 10-15 minutes more, stirring every 5 minutes, just until the eggs are set but still soft.