Resting a layered dish after assembly allows flavors to meld and ingredients to settle, resulting in a more cohesive and flavorful final product. This also makes slicing and serving easier.
When you layer a dish, whether it's a lasagna, a trifle, or a layered salad, the individual ingredients are initially distinct. Resting allows the flavors to transfer and harmonize. For example, in a lasagna, the sauce will seep into the pasta, the cheese will soften and bind the layers together, and the herbs will infuse their aroma throughout the dish. This melding process creates a more balanced and complex flavor profile. Furthermore, resting allows the dish to firm up, making it easier to cut clean slices without the layers sliding apart. The time required for resting varies depending on the dish; some may benefit from just 30 minutes, while others might need several hours or even overnight in the refrigerator. The key is to allow sufficient time for the flavors to develop and the structure to stabilize.
When resting a hot layered dish, loosely cover it with foil to prevent the top from drying out while still allowing steam to escape. This prevents condensation from making the top layer soggy.