The perfect make-ahead Martha Stewart Christmas Breakfast Casserole for a festive and stress-free holiday morning. This savory dish is layered with sourdough bread, pork sausage, and nutty Gruyère cheese, all soaked in a rich egg custard and baked until golden and puffy.
Ingredients
For the Casserole:
- 1 lb pork breakfast sausage
- 1 large yellow onion, chopped
- 1 (1-pound) loaf of sourdough bread, cut into 1-inch cubes
- 2 cups shredded Gruyère cheese
- 1/2 cup grated Parmesan cheese
For the Egg Custard:
- 8 large eggs
- 2 cups whole milk
- 1 cup heavy cream
- 1 tbsp Dijon mustard
- 1 tsp salt
- 1/2 tsp black pepper
- 1/4 tsp ground nutmeg
Instructions
- Cook sausage and onion in a skillet until browned. Drain the grease.
- In a large bowl, combine bread cubes, sausage mixture, and cheeses. Transfer to a greased 9×13-inch baking dish.
- In the same bowl, whisk together all egg custard ingredients.
- Pour the custard evenly over the bread mixture. Cover and refrigerate for at least 8 hours or overnight.
- Preheat oven to 350°F (175°C). Let the casserole sit at room temperature for 30 minutes.
- Bake uncovered for 50-60 minutes until golden and set. Let rest for 10 minutes before serving.