This strata is the best breakfast casserole I have ever had. Ivy G. introduced me to this dish. It’s an amazing recipe that is sure to be a hit. Note: This brunch dish is delicious with spinach, but feel free to substitute any other steamed vegetable such as chard, asparagus or broccoli. Sauteed mushrooms are a great addition as well.
1 (10-oz) package frozen spinach, thawed (or fresh spinach, lightly steamed)
1 1/2 cups finely chopped onion (1 large)
3 tablespoons unsalted butter
1 teaspoon salt
1/2 teaspoon black pepper
1/4 teaspoon freshly grated nutmeg
8 cups cubed (1 inch) French or Italian bread (1/2 lb)
6 oz coarsely grated Gruyère (2 cups)
2 oz finely grated Parmigiano-Reggiano (1 cup)
2 3/4 cups milk
9 large eggs
2 tablespoons Dijon mustard
Squeeze handfuls of spinach to remove as much liquid as possible, then finely chop.
Cook onion in butter in a large heavy skillet over moderate heat, stirring, until soft, 4 to 5 minutes. Add 1/2 teaspoon salt, 1/4 teaspoon pepper, and nutmeg and cook, stirring for 1 minute. Add spinach, then remove from heat.
Butter a 3-quart gratin dish or other shallow ceramic baking dish. Toss together the bread cubes, spinach mixture, and cheeses. Place evenly in the baking dish.
Whisk together milk, eggs, mustard, and remaining 1/2 teaspoon salt and 1/4 teaspoon pepper in a large bowl and pour evenly over strata. Chill strata, covered with plastic wrap, at least 8 hours (for bread to absorb custard), up to one day ahead.
Preheat oven to 350°F. Let strata stand at room temperature 30 minutes.
Bake strata, uncovered, in middle of oven until puffed, golden brown, and cooked through, 45 to 55 minutes. Let stand 5 minutes before serving.
Adapted from Spinach and Cheese Strata Recipe at Epicurious.com.