Buttery Breakfast Casserole with Sausage
A savory breakfast casserole combining toasted croissants, Italian sausage, and creamy custard baked until golden. Gruyère cheese and fresh sage add depth while the buttery croissants provide textural contrast. Perfect for brunch gatherings or make-ahead breakfast for a crowd. This version uses both buttermilk and heavy cream for a rich, velvety base that sets it apart from lighter casserole recipes.
Ingredients
- ½ cup heavy cream, or half and half
- ½ teaspoon freshly ground black pepper
- 4 ounces Gruyère, shreddedaged cheddar or Emmental1:1dairyadds dairy
similar nutty flavor and melt
- ½ bunch scallions, sliced, divided
- 4 eggs
- ½ tablespoon extra-virgin olive oil
- 1 teaspoon fresh sage, finely chopped
- 1 ½ cups buttermilk or whole milk
- ½ pound croissants, split lengthwisebrioche or challah1:1bread
similar richness, slightly less flaky
- ⅓ pound sweet Italian sausagemild breakfast sausage or turkey sausage1:1protein
leaner option
- ⅝ teaspoon salt
Instructions
- 1
Preheat oven to 500F. Place croissants on a dish and toast until golden brown, about 5-10 minutes. Cool, then tear into bite-size pieces.
- 2
Heat olive oil in a large skillet over medium-high heat. Add scallions and sausage, stirring frequently until browned, about 5 minutes. Stir in sage and remove from heat.
- 3
Combine toasted croissants and sausage mixture in a bowl. In another bowl, whisk together eggs, milk, cream, 1 1/2 cups cheese, salt, and pepper.
- 4
Oil a 9x13-inch baking dish. Add croissant-sausage mixture and spread evenly. Pour custard over and press gently to help absorption. Cover with plastic wrap and refrigerate at least 4 hours or overnight.
- 5
Preheat oven to 350F. Sprinkle remaining cheese over the casserole. Bake until golden brown and firm to the touch, approximately 45 minutes.
- 6
Let stand 10 minutes. Garnish with sliced scallion tops and serve.
Tips
Toast croissants just until golden to maintain structural integrity during soaking. Over-toasting will cause them to disintegrate in the custard.
Overnight refrigeration allows croissants to fully absorb the custard, creating a cohesive texture. Don't skip this step for best results.
Gently press croissants when pouring custard to distribute evenly without breaking them apart.
Good to Know
Cover and refrigerate up to 3 days. Do not freeze after assembly due to custard texture changes.
Assemble through refrigeration step up to 24 hours in advance. Bake fresh when ready to serve.
Serve warm from the oven with fresh fruit or a simple green salad. Pairs well with coffee or sparkling mimosas.
Common Mistakes
Don't skip the 4-hour minimum chill time to avoid a soupy casserole.
Don't overbake to avoid a rubbery custard and dried-out croissants.
Don't skip the 10-minute rest period to allow the custard to set.
Substitutions
Dairy-Free Swaps
similar nutty flavor and melt
General Alternatives
similar richness, slightly less flaky
leaner option
FAQ
Can I make this casserole the day before?
Yes. Assemble through the refrigeration step up to 24 hours ahead. Cover tightly and bake fresh when needed. The overnight soak actually improves flavor melding.
What if my casserole looks underdone after 45 minutes?
Tent with foil and bake 10-15 minutes longer. The custard should jiggle slightly in the center when gently shaken but firm at edges. Carryover cooking during rest period helps finalize texture.
How long does a baked casserole keep?
Store covered in the refrigerator for up to 3 days. Reheat at 325F for 15-20 minutes covered with foil. Do not freeze after baking due to custard texture breakdown.