What is the key ingredient in a café au lait?

The key ingredient in a café au lait is regular coffee with steamed milk. This popular beverage is typically made by combining brewed coffee with an equal amount of steamed milk or hot milk. Unlike lattes or cappuccinos, which primarily use espresso as a base, café au lait is distinguished by its use of brewed coffee, making it a favored choice for those who enjoy a milder coffee flavor complemented by the creaminess of the milk. The balance between the coffee and milk creates a rich, smooth texture that is both comforting and indulgent.