In addition to apples, what ingredient is crucial for making a traditional tarte Tatin?

In making a traditional tarte Tatin, butter is a crucial ingredient because it plays a key role in the caramelization process that gives the tart its distinctive flavor and texture. When you prepare tarte Tatin, the apples are cooked in a combination of sugar and butter. The butter assists in creating a rich, golden caramel that envelops the apples, enhancing their sweetness while providing a luxurious mouthfeel. The quality and quantity of butter can significantly impact the final result, affecting both the taste and the overall texture of the dish, making it essential for achieving authenticity and depth in flavors. In this context, while other ingredients can certainly complement the dish, butter is foundational to the traditional recipe.