Make this strata a day ahead of time and pop in the oven in the morning for a calm (and delicious) start to the day.
CourseBreakfast, Main Dish
110 oz packagefrozen spinach, thawed and choppedand squeezed of excess liquid
1 1/2cupsonion, finely chopped
3 Tbspunsalted butter
1/4tspnutmeg, freshly grated
8cupsFrench or Italian bread, in 1-inch cubes
2cupsGruyere cheese, coarsely grated
1 1/4cupsParmesan, finely grated
Sauté onion in butter in a large, heavy skillet over medium heat until soft, about 5 minutes. Add ½
teaspoon salt, ¼ teaspoon pepper and nutmeg, and continue cooking for 1 minute.
Stir in spinach, remove from heat and set aside.
Spread one-third of the bread cubes in a well-buttered 3-quart gratin dish or other ceramic baking dish. Top with one-third of spinach mixture and one-third of each cheese. Repeat layering twice with remaining bread, spinach and cheese.
Whisk eggs, milk, mustard and remaining ½ teaspoon salt and ¼ teaspoon pepper together in a large bowl and pour evenly over strata. Cover with plastic wrap and chill strata for eat least 8 hours or up to a day.
The next day, let it stand at room temperature for 30 minutes while preheating the oven to 350°F. Bake strata, uncovered, in middle of oven until puffed, golden brown, and cooked through, 45–55 minutes. Let stand 5 minutes before serving.