How do you make an egg bake that slices neatly yet stays tender in the middle? Cook the vegetables first, give the bread time to absorb the eggs, and check the center with a thermometer. This breakfast egg casserole recipe brings those steps together in one generous dish for a relaxed morning meal.
Many recipes for breakfast casseroles invite you to add whatever is in the refrigerator. A little restraint helps: keep the proportions of eggs, milk, and bread steady, then vary the cheese or herbs. This recipe for a breakfast bake uses mushrooms and spinach for a savory filling and makes six satisfying servings.
Breakfast Bake Recipe: Ingredients and Equipment
Allow about 25 minutes for preparation, 15 minutes for soaking, and 35 to 45 minutes in the oven. You will need a skillet, a mixing bowl, a whisk, a 2-quart baking dish approximately 8 inches square, and an instant-read food thermometer.
- 1 tablespoon olive oil, plus a little for the dish
- 8 ounces mushrooms, sliced
- 1 small yellow onion, diced, about 3/4 cup
- 3 ounces fresh baby spinach, roughly chopped
- 6 large eggs
- 1 1/2 cups whole milk
- 1 teaspoon Dijon mustard
- 1/2 teaspoon kosher salt
- 1/4 teaspoon black pepper
- 4 cups day-old bread, cut into 1-inch cubes, about 6 ounces
- 1 cup shredded sharp cheddar, about 4 ounces
- 2 tablespoons chopped fresh chives, plus more for serving
A sturdy loaf of white or whole-wheat bread works well. If yours is very fresh, spread the cubes on a baking sheet and dry them in a 300°F oven for about 10 minutes. They should feel dry at the edges, without becoming hard croutons. Let them cool while you prepare the filling.
Cook the filling first
Heat the oven to 350°F and lightly oil the baking dish. Heat the tablespoon of oil in a large skillet over medium heat. Add the mushrooms and onion and cook, stirring occasionally, for 8 to 10 minutes, until the mushrooms release their liquid and the pan looks nearly dry. Add the spinach and stir for 1 to 2 minutes, until wilted. Let the mixture cool for about 10 minutes.
Mushrooms and spinach carry a surprising amount of water. Cooking some of it away concentrates their flavor and leaves less liquid to pool around the eggs. Spread the vegetables in the pan while they cool; this helps them lose heat faster before they meet the egg mixture.
Assemble and bake
Whisk the eggs, milk, mustard, salt, and pepper in a large bowl until evenly blended. Fold in the bread, cooled vegetables, cheddar, and chives. Transfer the mixture to the prepared dish and press the bread gently into the liquid. Let it stand for 15 minutes so the cubes can soak through. The top will look uneven, with a few bread corners peeking out.
Bake uncovered for 35 to 45 minutes, until puffed, lightly golden, and set at the edges. Insert the thermometer into the center, avoiding the bottom of the dish; the breakfast casserole bake is ready when the center reaches 165°F. Begin checking at 35 minutes, since dish material and oven temperatures can change the timing.
Rest the dish for 10 minutes before cutting it into six squares. The eggs firm a little as they rest, making each portion easier to lift. Serve with sliced oranges or a crisp green salad, and put extra chives on the table for a fresh finish.
Adjust the texture and serve
In this breakfast bake recipe, bread gives the eggs a soft, custardy structure. For a breakfast bake with bread, soaking matters: dry cubes need a few minutes to draw liquid into their centers, while a quick dip can leave chewy, dry pockets. For a more compact slice, press the cubes down gently rather than packing them tightly. Too much bread can absorb the mixture before it surrounds all the filling.
Among breakfast casserole recipes, this one is especially adaptable to a different cheese. Try the same amount of shredded Monterey Jack for a milder flavor, or use half cheddar and half Swiss. Keep the total at one cup so the egg mixture remains the main structure. A breakfast casserole recipe with Swiss will taste nuttier. A brunch egg casserole can sit at the center of a spread with fruit, toast, and coffee, or make a substantial breakfast on its own.
For a variation, start with the same cooked vegetables: add a pinch of smoked paprika to the eggs or exchange the chives for chopped parsley. If using another moist vegetable, cook it until its excess liquid has evaporated and cool it before mixing. Aim for roughly the same volume of filling so the center cooks in a similar time.
Recipes for breakfast casseroles with bread make appealing leftovers. Divide the cooked portions into shallow containers and refrigerate within two hours of cooking, or within one hour if the temperature is above 90°F. Store at 40°F or below for three to four days. Reheat portions to 165°F, checking the center with a thermometer.
Check the center
The edges may look finished before the middle is ready. If the center is wet and loose when you gently shake the dish, or the thermometer reads below 165°F, return it to the oven for 5 minutes and check again. If the top is already well browned, cover it loosely with foil while the middle finishes. Repeat until the center reaches 165°F, then let the dish rest before serving.