Breakfast Casserole With Biscuits and Chicken Sausage

• The filling bakes first, so biscuit dough meets a hot, mostly set surface instead of raw custard. That simple sequence avoids a pale, damp underside.
• Chicken sausage brings seasoning without separate gravy or a long ingredient list. Spinach folds into eggs, adding color without another pan.
• A 9-by-13-inch dish cuts into twelve squares with clear biscuit portions. It moves from refrigerator to microwave without requiring a fork-and-plate production.
• Using refrigerated biscuits keeps morning assembly focused on filling and timing. Choose dough with eight biscuits so the top is evenly covered.

• 1 tablespoon olive oil (14 g)
• 12 ounces chicken breakfast sausage, casings removed (340 g)
• 1 medium yellow onion, finely diced (150 g)
• 5 ounces baby spinach, roughly chopped (142 g)
• 10 large eggs (500 g)
• 1 cup whole milk (240 g)
• 1 teaspoon kosher salt (6 g)
• 1/2 teaspoon black pepper (1 g)
• 1 teaspoon garlic powder (3 g)
• 2 cups shredded sharp cheddar cheese (226 g)
• 1 tube refrigerated buttermilk biscuit dough, 8 biscuits (453 g)

Ingredient notes

• Chicken breakfast sausage gives the filling a seasoned base with less chopping. Use cooked sausage only if warmed briefly with onion; otherwise brown and crumble raw sausage before the eggs enter dish for even pieces.
• Refrigerated buttermilk biscuit dough is the convenient choice here because the pieces bake separately. Keep it cold until topping time, then arrange the eight rounds with small gaps so heat can reach their sides evenly.
• Whole milk makes the egg mixture fluid enough to settle around the sausage and spinach. Lower-fat milk works, though the baked filling may be slightly less rich and should still be whisked until completely uniform.
• Baby spinach needs only a brief wilt in the skillet before it joins the casserole. Squeeze no moisture from it; simply cook until collapsed, then let steam escape for a minute while egg mixture is whisked.
• Sharp cheddar carries through the egg custard better than a very mild cheese. Shred a block when possible for looser melting, or use pre-shredded cheese and scatter it evenly so every cut square gets some.

1. 1Heat the oven

   Set a rack in the center and heat the oven to 375°F. Butter a 9-by-13-inch baking dish, including the corners. Put a large skillet over medium heat while the oven comes up, which keeps assembly moving without rushing the eggs at the end.

2. 2Cook the filling

   Add olive oil and chicken sausage to the skillet. Break the sausage into small crumbles and cook until browned. Add onion and cook until softened, then stir in spinach just until collapsed. Remove the skillet from heat and spread the mixture across the prepared dish.

   

3. 3Whisk the custard

   Whisk eggs, milk, salt, pepper, and garlic powder in a large bowl until the yolks disappear completely. Stir in three-quarters of the cheddar. Pour this mixture slowly over the sausage and vegetables, then use a spoon to settle any exposed spinach under the liquid.

4. 4Start the casserole

   Bake the uncovered casserole for 20 minutes. The edges should look set, while the center will still jiggle when the dish is nudged. This first bake gives the egg layer enough structure to support biscuits without pressing them into a wet filling.

   

5. 5Add the biscuits

   Separate the biscuit dough into eight rounds. Arrange them in two rows of four over the partly baked casserole, leaving narrow gaps between rounds. Sprinkle the remaining cheddar over and around the biscuits rather than burying their tops, which helps the dough brown.

6. 6Finish and rest

   Return the dish to the oven for 18 to 22 minutes, until biscuit tops are deeply golden and the center reaches 160°F. Rest for 10 minutes before cutting twelve squares. The brief pause firms the filling and makes portions easier to lift from the dish.

• Use a metal or ceramic 9-by-13-inch dish, not a deeper casserole pan. The shallower depth helps the egg layer set before biscuit dough is added, keeping the timing predictable.
• Brown raw sausage until it is broken into small, loose pieces. Large chunks create gaps in the filling and make the biscuit layer sit unevenly across the surface.
• Do not add the biscuits early to save a step. Their bottoms need the partly set egg surface, and the twenty-minute head start is the useful part of this method.
• Check the center rather than judging only by browned biscuits. If the tops are dark enough before the center is ready, place foil loosely over the dish for the remaining bake time.

Cut the casserole into twelve squares and use a thin spatula to get beneath each biscuit portion. Pair it with fruit, sliced oranges, or a simple tomato salad for a lighter plate. For a larger brunch spread, add roasted potatoes and coffee, then let the casserole carry the eggs and savory component. Hot sauce, chopped scallions, and extra black pepper work well at the table without changing the baked dish.