Croissant Breakfast Casserole

Torn day-old croissants soak up a mustard-spiked egg custard, then bake into something between a savory bread pudding and a souffle. The ragged edges go shatteringly crisp while the centers stay rich and custardy. Bacon, sweet onion, rosemary and nutty gruyere run through every bite. Assemble the night before and slide it into the oven while the coffee brews.

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Prep Time 25

Cook Time 55

Total Time 1 40

Servings: 10 People

Course: Breakfast

Cuisine: American

Calories: 545

Ingredients Equipment Method Notes

Ingredients

1 tbsp butter softened, for the baking dish
9 day-old croissants about 1.5 lb, torn into large chunks
12 oz thick-cut bacon cut into 1/2 inch pieces
1 medium yellow onion finely diced
1 tbsp fresh rosemary finely chopped
10 oz gruyere cheese shredded, about 3.5 cups
12 large eggs
3 cups half-and-half not milk
2 tbsp coarse Dijon mustard or brown mustard
2 tsp kosher salt
1 tsp freshly ground black pepper
0.25 tsp freshly grated nutmeg optional

Equipment

1 9x13 inch baking dish glass or ceramic
1 Large Skillet cast iron works well
1 Large mixing bowl
1 Whisk
1 Slotted spoon

Method

Butter a 9x13 inch baking dish generously, including the corners and up the sides.
Tear the croissants by hand into chunks about 2 inches across. Tear, do not slice. The ragged edges are what crisp up in the oven. Scatter them evenly in the baking dish.
Cook the bacon in a large skillet over medium heat, stirring occasionally, until browned and crisp at the edges, 8 to 10 minutes. Lift it out with a slotted spoon onto a paper towel lined plate.
Pour off all but about 2 tablespoons of the bacon fat. Add the onion and rosemary and cook over medium heat until the onion is soft and translucent, 3 to 4 minutes. Lift the onion out with the slotted spoon, leaving the grease behind in the pan so it does not pool in the casserole.
Scatter the bacon, onion mixture and shredded gruyere over the croissants, pushing some down into the gaps between the pieces so every layer gets cheese and meat.
In a large bowl, whisk the eggs until the yolks and whites are fully combined and slightly foamy. Whisk in the half-and-half, mustard, salt, pepper and nutmeg until smooth with no streaks of mustard left.
Pour the custard slowly and evenly over the whole dish. Press the croissants down lightly with your palm or the back of a spoon so the tops are moistened but still sitting above the custard line.
Let the dish stand at room temperature for 20 to 30 minutes. Do not soak it longer than that or the croissants saturate and you lose the crisp top. For a make-ahead, cover and refrigerate overnight instead.
Heat the oven to 350 F. Bake the casserole uncovered on a middle rack for 45 to 60 minutes, until it is puffed, deeply golden on top and set in the center. Press the middle gently with a spoon. No liquid should rise around it. If the top browns too fast, tent it loosely with foil for the last 15 minutes.
Rest the casserole on a rack for 10 minutes so the custard firms, then cut into squares and serve warm.

Notes

Use day-old croissants. Fresh ones collapse into mush. If yours are soft, tear them and toast on a sheet pan at 300 F for 10 minutes, then cool.

Do not swap in milk for the half-and-half. The custard will not set and the casserole weeps liquid.

Make-ahead: assemble through the custard, cover tightly and refrigerate up to 16 hours. Let it sit at room temperature 30 minutes before baking and add 5 to 10 minutes to the bake time.

Serve with fresh fruit or a simple fruit salad, breakfast potatoes, hot coffee and mimosas or Bloody Marys.

Leftovers keep 3 days covered in the fridge. Reheat uncovered at 325 F for 15 minutes to bring the top back to crisp.

Swaps: breakfast sausage or Italian sausage for the bacon, smoked gouda or sharp cheddar for the gruyere, thyme or sage for the rosemary.