Classic Casserole Recipe

Cook bacon

If using bacon: preheat oven to 400°F (200°C) or heat a skillet over medium. Arrange bacon in a single layer on a rimmed baking sheet and bake 12–18 minutes until crisp, or cook in skillet until browned and crisp. Drain on paper towels, then chop into 1/2-inch pieces. Set aside.

Cook sausage

If using breakfast sausage: heat a skillet over medium, add sausage and cook, breaking up with a spoon, until fully browned and cooked through (about 7–10 minutes). Drain excess fat if very greasy. Set aside to cool slightly.

Preheat oven to 375°F (190°C). In a medium skillet, heat 1 tablespoon butter or oil over medium heat. Add the finely diced onion and a pinch of salt; sauté until translucent and just beginning to brown, about 5–7 minutes. Remove from heat and let cool 2–3 minutes.

In a large bowl, whisk together the 8 eggs, 2 cups half-and-half (or milk), 1 teaspoon salt, 1 teaspoon black pepper, and 1/2 teaspoon dry mustard (if using) until smooth and combined.

Prepare a 9x13-inch (23x33 cm) baking dish: butter the dish or spray with nonstick spray. If you prefer a slightly denser casserole, line the bottom with half of the shredded cheddar (about 1 cup).

Combine proteins: in a medium bowl, mix the cooked chopped bacon OR the cooked crumbled sausage (use one or the other, not both). Evenly distribute the chosen protein over the bottom of the prepared baking dish.

Scatter the sautéed onions over the protein layer.

Sprinkle the remaining shredded cheddar (or the full 2 cups if you didn't line the bottom) evenly over the onions and protein.

Pour the egg and milk mixture evenly over the layers in the baking dish. Gently press down with a spatula so the liquid distributes and soaks into the layers. Let the assembled casserole rest 5–10 minutes so the liquid is absorbed; this also helps reduce bubbling during baking.

Preheat oven (if not already) to 375°F (190°C). Take 8 store-bought biscuits and crumble them with your hands or pulse 2–3 times in a food processor until coarse crumbs form (about 1/2–3/4 inch pieces). Toss the crumbs with 2 tablespoons melted butter until evenly coated.

Scatter the buttered biscuit crumbs evenly over the top of the assembled casserole for a crunchy, biscuit-like topping.

Bake the casserole in the preheated 375°F (190°C) oven for 30–40 minutes, until the center is set (a knife inserted in the center should come out mostly clean) and the topping is golden brown. If the topping browns too quickly, loosely tent the dish with foil for the last 10–15 minutes.

Remove from oven and let rest 10 minutes before serving to allow the eggs to finish setting. Garnish with chopped fresh parsley or chives if desired.