Why are crisp meringues often classified as pastries?

Crisp meringues are classified as pastries primarily because they can be used to create a wide range of desserts. Meringues are versatile in their applications; they can be transformed into layers in desserts like pavlova, used as a topping for pies, or piped into various shapes for garnishing other sweets. This ability to contribute to multiple dessert forms showcases their important role in the pastry world.

In contrast, the other options do not align with the classification of meringues as pastries. Meringues are specifically made without the use of temperature control in a continuous manner during baking, but the critical factor in their pastry classification involves their versatility, not the baking temperature itself. The presence of a strong butter content isn't applicable to meringues, as they are generally egg white-based and do not rely on butter for their structure or flavor. Finally, meringues are not made with yeast, as they do not require fermentation or rising, which distinguishes them from traditional pastries that rely on yeast for leavening.