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There is something truly magical about waking up to a warm, hearty breakfast that feels both indulgent and comforting. The Sausage and Sage Croissant Breakfast Casserole Recipe offers exactly that—a beautiful balance of flaky, buttery croissants, savory Italian sausage, fragrant fresh sage, and the creamy richness of Gruyère cheese. Perfect for a brunch gathering or a special weekend treat, this casserole brings together simple ingredients in a way that’s sure to delight your senses and fill your kitchen with irresistible aromas.

Ingredients You’ll Need
This recipe showcases how straightforward yet well-chosen ingredients can come together to create a dish bursting with flavor, texture, and color. Each element plays an essential role, from the buttery croissants adding flakiness to the fresh sage infusing an herbaceous lift, creating a layered and satisfying breakfast experience.
- 1-2 tablespoons butter, softened: Used to generously grease the baking dish, preventing sticking and adding richness.
- 1 pound croissants (about 5 to 7), split in half lengthwise: The buttery base providing that beautiful flaky texture and absorbing the custard.
- 1 tablespoon vegetable oil: For browning the sausage evenly without burning.
- 1 bunch scallions (6 to 7), white and light green parts thinly sliced, greens reserved: Adds a mild onion flavor and fresh color.
- 3/4 pound sweet Italian sausage, casings removed: Provides savory, spiced protein that’s tender and flavorful.
- 2 teaspoons fresh sage, finely chopped: Brings an earthy, aromatic note that perfectly complements the sausage.
- 8 large eggs, at room temperature: The binding custard base, creating a creamy, tender texture.
- 3 cups whole milk: Adds moisture and richness to the egg mixture.
- 1 cup heavy cream: Elevates the custard’s creaminess for a luscious finish.
- 1 1/2 cups Gruyère cheese, grated (reserve 1/2 cup for topping): Nutty and melty cheese that adds depth and gooeyness.
- 1 1/4 teaspoons salt: Enhances all the flavors throughout the dish.
- 1 teaspoon black pepper: Adds just enough gentle heat and spice.
- 1 tablespoon fresh sage, finely chopped (for topping): A fresh sprinkle to brighten and garnish.
- Reserved green parts of scallions: A subtle, crisp green garnish to finish beautifully.
How to Make Sausage and Sage Croissant Breakfast Casserole Recipe
Step 1: Grease Baking Dish
Start by generously greasing a 9×13 inch baking dish with 1 to 2 tablespoons of softened butter. This simple step ensures that your casserole won’t stick and adds a subtle buttery note to the edges. Once greased, preheat your oven to 350ºF (177ºC) so it’s ready for later baking.
Step 2: Toast Croissants
Take your croissant halves and arrange them cut-side up on a large baking sheet. Pop them into the oven for just 2 to 4 minutes until they achieve a light golden-brown toast. This brief toasting adds extra texture and helps the croissants hold their shape once soaked with the egg custard. After baking, let them cool slightly so you can tear them into large, bite-sized pieces.
Step 3: Cook Sausage
Heat 1 tablespoon of vegetable oil in a skillet over medium-high heat. Add the sweet Italian sausage, breaking it up with a spatula as it cooks. Brown the sausage thoroughly, about 6 to 8 minutes, until no pink remains and it develops rich caramelized bits. Browning is key—it adds flavor and texture to the casserole.
Step 4: Add Scallions
Into the sausage, stir the thinly sliced white and light green parts of your scallions. Let them cook together until the scallions soften and become fragrant. This step infuses the meat mixture with a mild onion-like sweetness that balances the richness.
Step 5: Incorporate Sage and Cool
Mix in the 2 teaspoons of chopped fresh sage, stirring well to distribute the herb’s warm, earthy flavor. Remove the skillet from heat and allow the sausage mixture to cool for 7 to 10 minutes before combining with eggs. Cooling is crucial to prevent the eggs from scrambling once mixed.
Step 6: Combine Croissants and Sausage Mixture
In a large mixing bowl, gently toss the toasted croissant pieces with the cooled sausage and scallion mixture. This ensures every bite gets the perfect balance of fluffy bread and savory meat.
Step 7: Prepare Egg Custard
In a separate bowl, whisk together the eggs, whole milk, heavy cream, 1 1/2 cups grated Gruyère, salt, and black pepper until completely smooth and uniform. This rich custard will soak into the croissant pieces, creating a soft, velvety texture that’s simply irresistible.
Step 8: Assemble Casserole
Pour the croissant and sausage mixture into your buttered baking dish, spreading it out evenly. Slowly pour the egg custard over the top, pressing down gently on the croissants to help them absorb the liquid fully. The soaking time is what makes this casserole so dreamy.
Step 9: Refrigerate
Cover the assembled casserole tightly with plastic wrap and refrigerate for at least 4 hours or overnight. This allows the custard to soak thoroughly into the croissant pieces and the flavors to gently meld, resulting in a more unified and luscious dish.
Step 10: Preheat Oven for Baking
When ready to bake, take the casserole out of the fridge and preheat your oven again to 350ºF (177ºC).
Step 11: Bake Casserole
Remove the plastic wrap, sprinkle the reserved 1/2 cup Gruyère cheese evenly on top, and bake uncovered for about 45 minutes. You’re looking for a golden brown top with a firm, set center. Once baked, let it sit for 10 minutes before serving—this resting allows the casserole to set and makes slicing neat and easy.
How to Serve Sausage and Sage Croissant Breakfast Casserole Recipe

Garnishes
Topping the warm casserole with reserved scallion greens and a sprinkle of freshly chopped sage adds a fresh, vibrant accent. Not only does this brighten the dish visually, but it also adds a lovely herbal lift to each bite, elevating the overall flavor balance.
Side Dishes
This casserole pairs beautifully with light and fresh sides. A crisp green salad with lemon vinaigrette or a simple fruit salad with berries and citrus contrasts perfectly with this rich dish, helping to round out the meal. You can also offer some tangy yogurt or a dollop of salsa for guests who like a flavor kick.
Creative Ways to Present
Consider serving this collage style, slicing squares onto beautifully rustic wooden boards or colorful platters to impress your brunch crowd. You can also make individual portions in ramekins for a personalized touch. For a festive occasion, garnish with edible flowers or finely chopped herbs to really wow your guests visually and gastronomically.
Make Ahead and Storage
Storing Leftovers
Leftover casserole keeps wonderfully in the fridge when covered tightly with foil or stored in an airtight container. It will stay fresh and flavorful for up to 3 days, making it a great make-ahead breakfast or easy reheatable meal.
Freezing
You can freeze leftovers in portioned airtight containers for up to 2 months. Just make sure to cool completely before freezing and label with the date. Thaw overnight in the fridge before reheating for best texture.
Reheating
To reheat, cover with foil and warm in a 350ºF (177ºC) oven for about 15-20 minutes, or until heated through. For quicker reheating, microwave individual servings on medium power in 30-second intervals, stirring or checking between to avoid dryness.
FAQs
Can I use other types of bread instead of croissants?
Absolutely! While croissants add a buttery, flaky dimension unique to this recipe, you can substitute with brioche or challah for a similarly rich texture. Just keep in mind that sturdier bread may absorb custard differently.
Do I have to use Gruyère cheese?
Gruyère adds a wonderful nutty flavor that melts beautifully, but you can swap it with other cheeses like Swiss, cheddar, or fontina depending on your preference. Just choose a good melting cheese to keep the casserole creamy.
Is it okay to prepare the casserole the night before?
Yes! Preparing it the night before and letting it soak in the fridge is recommended. This resting period enhances flavor melding and texture, making your morning baking effortless and delicious.
Can I make this recipe vegetarian?
For a vegetarian twist, omit the sausage and add sautéed mushrooms, bell peppers, or spinach. You can also use plant-based sausage alternatives to keep the hearty protein element.
How do I know when the casserole is done baking?
Your casserole is ready when the top is golden brown and the center is set and firm to the touch. A knife inserted in the middle should come out clean or with just a few moist crumbs.
Final Thoughts
If you’re looking to impress family or friends with an effortless yet extraordinary breakfast, this Sausage and Sage Croissant Breakfast Casserole Recipe is your answer. Its layers of flavor, comforting textures, and rich aromas create a breakfast experience that feels both luxurious and homey. Give it a try for your next brunch, and watch it quickly become a beloved staple in your kitchen!
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Print
Sausage and Sage Croissant Breakfast Casserole Recipe
- Prep Time: 20 minutes
- Cook Time: 55 minutes
- Total Time: 5 hours 15 minutes
- Yield: 12 servings
- Category: Breakfast Casserole
- Method: Baking
- Cuisine: American
Description
This Sausage and Sage Croissant Breakfast Casserole is a deliciously savory morning dish combining buttery croissants, sweet Italian sausage, fresh sage, and creamy Gruyère cheese baked into a custardy casserole. It’s perfect for brunch gatherings or make-ahead breakfasts, soaking overnight to meld flavors and bake to golden perfection. The rich custard and crispy croissant pieces create a satisfying comfort food with a fresh herbal brightness.
Ingredients
Casserole Base and Toppings
- 1–2 tablespoons butter, softened (for greasing dish)
- 1 pound croissants (about 5 to 7), split in half lengthwise
- 1/2 cup Gruyère cheese, grated (for topping)
- Reserved green parts of scallions (for garnish)
- 1 tablespoon fresh sage, finely chopped (for garnish)
Sausage Mixture
- 1 tablespoon vegetable oil
- 3/4 pound sweet Italian sausage, casings removed
- 1 bunch scallions (6 to 7), white and light green parts thinly sliced
- 2 teaspoons fresh sage, finely chopped
Egg Custard
- 8 large eggs, at room temperature
- 3 cups whole milk
- 1 cup heavy cream
- 1 1/2 cups Gruyère cheese, grated
- 1 1/4 teaspoons salt
- 1 teaspoon black pepper
Instructions
- Grease Baking Dish: Use 1-2 tablespoons of softened butter to generously grease a 9×13 inch baking dish. Set it aside. Preheat your oven to 350ºF (177ºC).
- Toast Croissants: Arrange croissant halves cut side up on a large baking sheet. Bake for 2 to 4 minutes until golden brown, then remove and let cool until manageable. Tear the croissants into large bite-sized pieces.
- Cook Sausage: Heat 1 tablespoon vegetable oil in a skillet over medium-high heat. Add the sweet Italian sausage, cooking and crumbling it until well browned and cooked through, about 6-8 minutes.
- Add Scallions: Stir in the sliced white and light green scallion parts into the sausage mixture. Continue cooking until scallions are softened.
- Incorporate Sage and Cool: Mix in 2 teaspoons of finely chopped fresh sage. Remove the skillet from heat and let the sausage mixture cool for 7-10 minutes to avoid cooking the eggs later.
- Combine Croissants and Sausage Mixture: In a large bowl, toss together the toasted croissant pieces and cooled sausage mixture to evenly distribute flavors.
- Prepare Egg Custard: In a separate large mixing bowl, whisk together 8 large eggs, 3 cups whole milk, 1 cup heavy cream, 1 1/2 cups grated Gruyère, 1 1/4 teaspoons salt, and 1 teaspoon black pepper until fully combined and smooth.
- Assemble Casserole: Pour the croissant and sausage mixture into the buttered baking dish and spread evenly. Pour the egg mixture over the top, gently pressing down the croissants so they absorb the liquid well.
- Refrigerate: Cover the assembled casserole tightly with plastic cling wrap. Refrigerate for at least 4 hours or overnight to let the custard soak thoroughly into the croissants and flavors meld.
- Preheat Oven for Baking: When ready to bake, preheat your oven again to 350ºF (177ºC).
- Bake Casserole: Remove the plastic wrap. Sprinkle the remaining 1/2 cup Gruyère cheese on top of the casserole. Bake uncovered for about 45 minutes or until the top is golden brown and the center is firm to the touch. Remove from oven and let sit for 10 minutes before serving.
- Garnish and Serve: Top the casserole with the reserved scallion greens and 1 tablespoon of chopped fresh sage for a fresh accent. Serve warm and enjoy your flavorful breakfast casserole.
Notes
- The casserole benefits from soaking overnight to allow the croissants to absorb the custard fully, improving texture and flavor.
- You can substitute Gruyère cheese with Swiss or Emmental cheese if preferred.
- Make sure the sausage mixture cools before combining with eggs to prevent scrambling the eggs prematurely.
- If fresh sage is unavailable, use 1 teaspoon dried sage but reduce slightly.
- Leftovers keep well refrigerated for up to 3 days and can be reheated in the oven or microwave.

