Buttery Breakfast Casserole is a make-ahead brunch bake of toasted croissants, browned sweet Italian sausage, scallions and sage in a rich egg, cream and Gruyère custard. It bakes up puffed and golden on top and soft underneath. Build it the night before a special breakfast or brunch; it serves 12.
How to make it: Toast the croissants, brown the sausage, pour the custard over everything and chill at least 4 hours or overnight. Bake at 350°F for about 45 minutes, until golden brown and firm.
Why You’ll Love It
- Done the night before: all the chopping, browning and whisking happens ahead.
- Short morning: about 45 minutes in the oven and a 10-minute rest.
- Feeds a crowd: one 9×13-inch dish gives you 12 servings for a holiday breakfast or a weekend brunch.
- Rich and golden: croissants, cream and Gruyère bake into a golden top over a soft custard.
Ingredient Notes
Croissants: One pound, split in half lengthwise and toasted cut side up.
Scallions: One bunch. The white and light green parts cook with the sausage; slice the dark greens and save them for the top.
Gruyère: Eight ounces, grated, is about 2 cups. Most goes into the custard; save the rest for the top.
Oil: Vegetable oil for browning the sausage. Extra-virgin olive oil works just as well.
Ingredients
- 1 to 2 tablespoons butter, softened, for the dish
- 1 pound croissants, about 5 to 7, split in half lengthwise
- 1 tablespoon vegetable oil
- 1 bunch scallions (6 to 7), white and light green parts thinly sliced, greens reserved for garnish
- 3/4 pound sweet Italian sausage, casings removed
- 2 teaspoons fresh sage, finely chopped, plus 1 tablespoon for garnish
- 8 large eggs
- 3 cups whole milk
- 1 cup heavy cream
- 8 ounces Gruyère cheese, grated (2 cups), divided
- 1 1/4 teaspoons salt
- 1 teaspoon black pepper
How to Make Buttery Breakfast Casserole
1. Prep the dish and oven. Grease a 9×13-inch baking dish with the softened butter and heat the oven to 350°F.
2. Toast the croissants. Arrange the croissant halves cut side up on a large baking sheet and bake for about 2 to 4 minutes, until golden brown. Let them cool, then tear them into large bite-size pieces.
3. Brown the sausage. Heat the oil in a skillet over medium-high heat. Add the sausage and cook, crumbling it, until well browned and cooked through to 160°F, about 6 to 8 minutes. Add the sliced scallions and cook until they soften.
4. Add the sage and cool. Stir in the 2 teaspoons of sage, take the skillet off the heat and let the mixture cool for 7 to 10 minutes.
5. Fill the dish. In a large bowl, toss the torn croissants with the cooled sausage mixture. Spread it evenly over the bottom of the baking dish.
6. Make the custard. In another bowl, whisk the eggs, milk, cream, 1 1/2 cups of the Gruyère, salt and pepper.
7. Soak and chill. Pour the custard over the croissants, pressing them down gently to help them absorb the liquid. Cover with plastic wrap and refrigerate for at least 4 hours or overnight.
8. Bake. Heat the oven to 350°F. Scatter the remaining 1/2 cup of Gruyère over the top and bake for about 45 minutes, until golden brown, firm to the touch and 165°F in the center.
9. Rest and garnish. Let the casserole sit for 10 minutes, then scatter the reserved scallion greens and 1 tablespoon of chopped sage over the top and serve.
The Night-Before Plan for Buttery Breakfast Casserole
Toast first. Toasting the croissants before you build the casserole adds caramelized notes that stand up to the browned sausage, the sage and the melted Gruyère.
Press, then wait. When the custard goes in, press the croissant pieces down gently so they soak it up. Then cover the dish and let the refrigerator do the rest for at least 4 hours, or overnight.
Time the morning. Slide the dish into the oven about an hour before you want to eat. That covers the 45-minute bake and the 10-minute rest.
Know when it’s done. The top should be puffed and golden brown, and the middle should feel firm to the touch and look set.
Tips for Success
How do I keep the croissants from burning?
Stay close to the oven while they toast. At 350°F they only need about 2 to 4 minutes. If you toast them hotter, at 500°F, give them 5 to 10 minutes and watch them even more carefully.
What if the top browns before the center is set?
Lay a sheet of foil loosely over the dish after about 30 minutes and let it finish baking underneath.
How big should the croissant pieces be?
Tear them into large bite-size pieces, about 2 to 3 inches. When you spread them in the dish, leave a few edges poking up above the custard for a golden finish.
Variations
- Bacon, cheddar and red pepper: Swap the sausage for 8 ounces of crisp thick-cut bacon and the Gruyère for 1 cup of mozzarella mixed with 1/2 cup of sharp white cheddar. Add a diced red bell pepper, and make a smaller custard of 7 eggs, 1 1/2 cups of whole milk, 1/2 cup of heavy cream, 2 teaspoons of Dijon mustard and a splash of hot sauce. Bake uncovered at 350°F for 40 to 45 minutes, until puffed and set.
- Ham, Gruyère and Havarti: Scatter 1 cup of shredded ham and 1/2 cup of Havarti chunks through the croissants with the Gruyère. For the custard, whisk 8 eggs with 2 cups of heavy cream, Dijon mustard, granulated garlic and a pinch of thyme. Bake covered with foil at 350°F for 30 to 45 minutes until set, then uncover and broil 2 to 3 minutes to brown the top.
Storage & Reheating
Keep the assembled casserole in the refrigerator until it goes into the oven. USDA FSIS says to refrigerate leftovers within 2 hours in shallow, covered containers and eat them within 3 to 4 days, or freeze them for 3 to 4 months. FSIS lists cream sauce among foods that don’t freeze well, so the custard may lose some quality, though it stays safe. Thaw it in the refrigerator or reheat it from frozen, which takes longer. Reheat covered in the oven or microwave until it reaches 165°F. Don’t reheat it in a slow cooker.
What to Serve With It
For a sweet dish on the same brunch table, bake overnight crème brûlée French toast or an easy cinnamon roll coffee cake. Feeding a bigger crowd? Add a second savory bake: a bacon, egg and cheese biscuit casserole, a sausage, egg and cream cheese hash brown breakfast casserole or a breakfast casserole with tater tots and sausage. For a smaller egg and cheese bake, try a homestyle bacon and cheese quiche.
Frequently Asked Questions
What makes a buttery breakfast casserole buttery?
The croissants. They give the casserole an especially rich base, and the name comes from them. The only butter the recipe adds on its own is the 1 to 2 tablespoons that grease the dish.
What cheese can I use instead of Gruyère?
Any smooth-melting, creamy cheese. Use the same 8 ounces, grated: 1 1/2 cups whisked into the custard and 1/2 cup scattered on top before baking.
Can I use a different sausage?
Yes. Plain sausage with the casings removed can replace the sweet Italian sausage in the same 3/4-pound amount. Brown it with the scallions exactly as in step 3.
How many croissants are in a pound?
About 5 to 7, depending on their size. Small croissants work too; tear them into pieces the same way.
Final Notes
Slice the scallion greens and chop the extra sage the night before as well, so the morning is only oven, rest and serve. If you have a question or make this, tell me how it turned out in the comments.
Buttery Breakfast Casserole
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Ingredients
- 1 to 2 tablespoons butter softened, for the dish
- 1 pound croissants about 5 to 7, split in half lengthwise
- 1 tablespoon vegetable oil
- 1 bunch scallions 6 to 7; white and light green parts thinly sliced, greens reserved for garnish
- 3/4 pound sweet Italian sausage casings removed
- 2 teaspoons fresh sage finely chopped, plus 1 tablespoon for garnish
- 8 large eggs
- 3 cups whole milk
- 1 cup heavy cream
- 8 ounces Gruyère cheese grated (2 cups), divided
- 1 1/4 teaspoons salt
- 1 teaspoon black pepper
Instructions
- Grease a 9x13-inch baking dish with the softened butter and heat the oven to 350°F.
- Arrange the croissant halves cut side up on a large baking sheet and bake for about 2 to 4 minutes, until golden brown. Let them cool, then tear them into large bite-size pieces.
- Heat the oil in a skillet over medium-high heat. Add the sausage and cook, crumbling it, until well browned and cooked through to 160°F, about 6 to 8 minutes. Add the sliced scallions and cook until they soften.
- Stir in the 2 teaspoons of sage, take the skillet off the heat and let the mixture cool for 7 to 10 minutes.
- In a large bowl, toss the torn croissants with the cooled sausage mixture. Spread it evenly over the bottom of the baking dish.
- In another bowl, whisk the eggs, milk, cream, 1 1/2 cups of the Gruyère, salt and pepper.
- Pour the custard over the croissants, pressing them down gently to help them absorb the liquid. Cover with plastic wrap and refrigerate for at least 4 hours or overnight.
- Heat the oven to 350°F. Scatter the remaining 1/2 cup of Gruyère over the top and bake for about 45 minutes, until golden brown, firm to the touch and 165°F in the center.
- Let the casserole sit for 10 minutes, then scatter the reserved scallion greens and 1 tablespoon of chopped sage over the top and serve.
