Overnight Sweet Potato Breakfast Casserole With Sausage and Eggs
A savory make-ahead breakfast bake with roasted sweet potato cubes, browned sausage, spinach and a twelve egg custard under sharp cheddar. Assemble it the night before and cut twelve squares from the dish in the morning.
Servings 12 squares
Ingredients
For the Sweet Potatoes
- 1 ½ pounds sweet potatoes peeled and cut into ½ inch cubes
- 2 tablespoons olive oil
- ½ teaspoon kosher salt
For the Sausage and Vegetables
- 1 pound bulk breakfast sausage
- 1 medium yellow onion diced
- 1 red bell pepper diced
- 3 cloves garlic minced
- 3 cups packed baby spinach chopped
For the Custard and Top
- 12 large eggs
- ½ cup whole milk
- ½ teaspoon kosher salt
- ½ teaspoon black pepper
- ¼ teaspoon ground cinnamon
- 1 ½ cups shredded sharp cheddar cheese
- 1 tablespoon butter for the dish
Instructions
Cook the Components
- Heat the oven to 425F. Toss the sweet potato cubes with the olive oil and ½ teaspoon kosher salt, spread them on a sheet pan, and roast 20 minutes until browned at the edges and tender. Do NOT skip this, raw cubes will not cook through in the custard.
- Cook the sausage in a large skillet over medium heat, breaking it up, about 8 minutes. Drain it well and set it aside, reserving a spoonful of fat in the pan.
- Cook the onion and bell pepper in the reserved fat for 6 minutes, add the garlic for 1 minute, then add the spinach and cook just until wilted.
- Tip the vegetables into a sieve and press hard with the back of a spoon to squeeze out the liquid. Wet greens are the main cause of a watery casserole.
Assemble and Bake
- Butter a 9 by 13 inch baking dish. Spread the roasted sweet potato, sausage and drained vegetables across the bottom in an even layer.
- Whisk the eggs with the milk, salt, black pepper and cinnamon until the mixture is a uniform yellow with no ropes of white left, then pour it slowly over the filling so it settles into the gaps.
- Scatter the cheddar evenly over the top, on the custard rather than stirred in, so it browns during the bake.
- To bake now: 350F for 35 to 40 minutes, uncovered. To make it ahead: cover tightly and refrigerate up to 24 hours, then let the dish sit on the counter for 30 minutes and bake 40 to 50 minutes.
- It is done when the center wobbles as one set piece rather than sloshing, the edges pull from the sides, and an instant read thermometer reads 160F in the middle.
- Rest 10 minutes before cutting, or the squares will slump. Cut into 12 squares and serve straight from the dish with hot sauce and sliced avocado.
Notes
- Cook the potato first: the custard sets in 35 to 40 minutes and raw ½ inch cubes need closer to 50, so raw cubes stay hard.
- Squeeze the greens: cooked spinach holds a lot of water and it all ends up in the bottom of the dish.
- Custard ratio: 12 eggs to ½ cup whole milk. More milk gives a casserole that weeps when you cut it.
- Doneness: 160F in the center, then a 10 minute rest for carryover.
- Overnight: assemble fully, refrigerate up to 24 hours, rest on the counter 30 minutes before baking and add 5 to 10 minutes.
- Shredded version: grate the sweet potato raw and press it into the bottom of the dish as a base if you want a hash brown style casserole with no pre-roasting.
- This is the savory casserole, not the marshmallow topped Thanksgiving side. The ¼ teaspoon of cinnamon reads as warmth against the sausage, not as sweetness.