Serves 6 to 8. Recipe is reprinted with permission from “Cook’s Illustrated All-Time Best Brunch” by America’s Test Kitchen editors.
Tips: Use the large holes of a box grater to grate the onion. The assembled omelet needs to sit in the refrigerator well covered, for at least 8 hours in order to achieve the desired consistency.
3 tablespoons unsalted butter, softened
10 slices hearty white sandwich bread
12 ounces cheddar cheese, shredded (3 cups)
8 large eggs
3 cups whole milk
1 small onion, grated
1 teaspoon salt
½ teaspoon pepper
1 teaspoon dry mustard
½ teaspoon hot sauce
1. Grease 13-by-9-inch baking dish. Spread butter evenly over one side of bread slices, then cut into 1-inch pieces. Scatter half of bread evenly in prepared dish and sprinkle with half of cheddar. Repeat with remaining bread and cheese.
2. Whisk eggs, milk, onion, salt, pepper, mustard and hot sauce together in bowl until well combined. Pour egg mixture evenly over bread and press lightly on bread to submerge. Wrap dish tightly with plastic wrap and refrigerate for at least 8 hours.
3. Adjust oven rack to middle position and heat oven to 350 degrees. Unwrap casserole and bake until puffed and golden, about 1 hour. Serve immediately.
24-Hour “Omelet” with sun-dried tomatoes and mozzarella
Substitute mozzarella cheese for cheddar. Add ½ cup grated Parmesan cheese and ½ cup oil-packed sun-dried tomatoes, patted dry and chopped, between 2 layers of bread in first step. Sprinkle 3 tablespoons minced fresh cilantro over top before serving.
24-Hour “Omelet” with pepper Jack and chipotle chile
Substitute pepper jack cheese for cheddar and 2 to 3 teaspoons minced canned chipotle chile in adobo sauce for dry mustard and hot sauce. Sprinkle 3 tablespoons minced fresh cilantro over top before serving.
To make ahead: Omelet, prepared through step 2, can be refrigerated for up to 24 hours.