This cheesy, golden, puffed casserole is all about the eggs, consisting of a rich custard, bread and cheese. The result is a melt-in-your-mouth texture that rivals even the fluffiest scrambled eggs.

To keep the egg flavor at the fore, we prepared a milk-based custard. Buttered white bread, cut into bite-size pieces and layered with tangy cheddar cheese, promised to melt right into the custard, bringing plenty of richness.

A small amount of grated onion and a bit of dry mustard and hot sauce added just enough complexity. Refrigerating the assembled omelet overnight is necessary to achieve the desired consistency. This also melds the flavors and saturates the bread.

All we had to do before brunch was bake it.

Cheesy and golden, this humble casserole puffed impressively above the rim of the baking dish, making it a tempting but unfussy centerpiece.

24-HOURS OMELET

By America’s Test Kitchen

• 3 tablespoons unsalted butter, softened
• 10 slices white sandwich bread
• 12 ounces cheddar cheese, shredded (3 cups)
• 8 large eggs
• 3 cups whole milk
• 1 small onion, grated
• 1 teaspoon salt
• 1/2 teaspoon pepper
• 1 teaspoon dry mustard
• 1/2 teaspoon hot sauce

Grease a 13-by-9-inch baking dish. Spread butter evenly over 1 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.

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 at least 8 hours.

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. Serves 6 to 8.

VARIATIONS

>> Substitute mozzarella cheese for cheddar. Add 1/2 cup grated Parmesan cheese and 1/2 cup oil-packed sun-dried tomatoes, patted dry and chopped, between layers of bread. Sprinkle 3 tablespoons minced fresh cilantro over top before serving.

>> Substitute pepper jack cheese for cheddar and 2 to 3 teaspoons minced canned chipotle chilies in adobo sauce for dry mustard and hot sauce. Sprinkle 3 tablespoons minced fresh cilantro over top before serving.

Approximate nutritional information, per serving: 442 calories, 28 g total fat, 14 g saturated fat, 279 mg cholesterol, 860 mg sodium, 25 g carbohydrate, 1 g fiber, 7 g sugar, 23 g protein.