Breakfast Strata with Spinach and Gruyère

From America's Test Kitchen Season 2: French Toast, Waffles, and Breakfast Strata

A classic breakfast dish, strata is easy to prepare, presents a variety of flavors, can feed a crowd, and perhaps best of all, can, and indeed should be made ahead of time. Too often, though, it is overloaded with fillings; we wanted a savory bread pudding with a balanced, well-seasoned filling. Recipes recommend all kinds of bread to use; we liked supermarket French or Italian loaves, which were neutral in flavor but had a sturdy texture. Rather than cubing the bread, which is often recommended, we sliced it to retain the layered quality of the dish and let the slices dry slightly (stale bread held up better than fresh). We used whole eggs and half-and-half for the custard, with a tad more dairy than eggs, and increased the amount of custard to saturate the bread more fully. A surprisingly successful addition to the custard was white wine, which we reduced to evaporate the alcohol; it brightened all the flavors. A key to ensuring cohesiveness in the strata was weighting it while it rested for at least one hour; this way, every piece of bread absorbed some custard. We kept our fillings minimal so they wouldn’t overwhelm the bread and custard, and we sautéed the filling ingredients before adding them to the casserole to keep the moisture from turning the dish watery.