The Ultimate Overnight Slow Cooker Breakfast Casserole Recipe

I perfected a slow cooker breakfast casserole that doubles as a Make Ahead Grab And Go Breakfast, and one unexpected ingredient is the reason you will want to read on.

I never expected a slow cooker could make breakfast this effortless, but here we are. The Ultimate Overnight Slow Cooker Breakfast Casserole somehow arrives at the table like it had secret help, full of eggs and melted sharp cheddar cheese that make people go quiet while they take the first bite.

Guests always nag me for the secret, and i smile and act like I meant to be that impressive. It’s perfect as a Make Ahead Grab And Go Breakfast for hectic mornings and also shows up on my list of Best Brunch Food Ideas when company calls.

You’ll be oddly proud.

Ingredients

• Eggs: High in protein and fat, makes the casserole gooey and filling.
• Milk/Cream: Adds richness and moisture, more cream makes it extra custardy and luxe.
• Breakfast sausage: Packed with savory fat and protein, gives lots of flavor, a little salty.
• Sharp cheddar: Sharp, melty cheese brings tang, protein and that craveable golden top.
• Hash browns or bread: Potatoes add carbs and texture; bread soaks custard, more bready comfort.
• Onion and bell pepper: Give sweet and slightly bitter notes, add minimal fiber and brightness.
• Chives or green onions: Mild onion punch, fresh herb lift, adds color and sharper finish.
• Butter or spray: Prevents sticking, adds buttery flavor and helps edges crisp up nicely.

Ingredient Quantities

• 12 large eggs
• 2 cups whole milk (or 1 1/2 cups milk + 1/2 cup heavy cream if you want it richer)
• 1 teaspoon kosher salt
• 1/2 teaspoon black pepper
• 1/2 teaspoon garlic powder
• 1 lb breakfast sausage, cooked and crumbled (about 4ish links)
• 3 cups shredded sharp cheddar cheese
• 4 cups frozen shredded hash browns, thawed, or 6 cups cubed day old bread
• 1/2 cup yellow onion, finely chopped
• 1/2 cup green bell pepper, diced
• 2 tablespoons chopped fresh chives or green onions, optional
• 2 tablespoons butter or cooking spray to grease slow cooker

How to Make this

1. Grease a 6 to 7 quart slow cooker with the butter or cooking spray so the casserole won’t stick, or line with foil for easier cleanup.

2. Cook the breakfast sausage in a skillet until browned, crumble and drain off excess fat; set aside.

3. If using frozen shredded hash browns, thaw and press out as much water as you can with a clean towel or paper towels; if using day old bread, cube it and toss the cubes with a little melted butter so they absorb custard better.

4. In a large bowl whisk together the 12 eggs, 2 cups whole milk (or 1 1/2 cups milk plus 1/2 cup heavy cream), 1 teaspoon kosher salt, 1/2 teaspoon black pepper and 1/2 teaspoon garlic powder until blended and slightly frothy.

5. Layer half the hash browns or bread in the bottom of the slow cooker, sprinkle half the chopped onion and half the diced green pepper, then half the crumbled sausage and half the shredded cheddar.

6. Pour half the egg mixture over that first layer so things start soaking evenly, then repeat with the remaining hash browns or bread, onions, peppers, sausage and cheese and pour the rest of the egg mixture on top.

7. Give it a quick gentle push so the custard settles into the layers, cover and cook on LOW for 7 to 8 hours (or HIGH for 3 to 4 hours) until the center is set and a knife comes out mostly clean; do not lift the lid during cooking unless absolutely needed.

8. If the edges brown too much or it looks like it might overcook, switch to the WARM setting for the last 20 to 30 minutes; let the casserole rest 10 to 15 minutes after cooking so it firms up and slices nicer.

9. Sprinkle the optional chopped chives or green onions on top before serving, slice into wedges and serve warm. Leftovers keep covered in the fridge for 3 to 4 days and reheat great in the microwave.

Equipment Needed

1. 6 to 7 quart slow cooker (big enough to hold the casserole)
2. Large skillet or frying pan to brown the breakfast sausage
3. Large mixing bowl for whisking the eggs and milk
4. Whisk (or a fork if you gotta) to beat the custard
5. Measuring cups and spoons for milk, eggs and seasonings
6. Chef’s knife and cutting board for the onion, pepper and chives
7. Spatula or slotted spoon to transfer sausage and help layer the casserole
8. Clean kitchen towels or paper towels to press thawed hash browns, and aluminum foil or nonstick spray to grease/line the slow cooker

FAQ

The Ultimate Overnight Slow Cooker Breakfast Casserole Recipe Substitutions and Variations

• Milk/cream: swap the 2 cups whole milk for 1 1/2 cups milk + 1/2 cup plain Greek yogurt or sour cream for a richer, silkier custard; for dairy free use 2 cups unsweetened oat or soy milk, just know it’ll be a bit thinner and may set faster.
• Breakfast sausage: replace 1 lb sausage with 8–10 slices bacon, cooked and chopped, or 12 oz diced ham; for a vegetarian option use 14 oz crumbled plant based sausage or browned, seasoned extra firm tofu.
• Sharp cheddar: use Monterey Jack or Gruyere for a milder/nuttier note, or pepper jack if you want some heat; dairy free shreds work 1:1, add a tablespoon nutritional yeast for more savory flavor.
• Hash browns / day old bread: swap 4 cups frozen shredded hash browns for 2 lbs small potatoes cut 1/2 inch and par roasted until just tender, or use 6 cups cubed brioche or sourdough for extra richness; tip, squeeze excess water from thawed hashbrowns or your casserole can get soggy.

Pro Tips

1) Stop a soggy middle: squeeze out as much water as you can from frozen taters, then toss them with a tablespoon of flour or powdered milk. It helps the custard set instead of turning watery, you’ll thank me later.

2) Big flavor comes from browning: really brown the sausage, onion and pepper instead of just softening them, that caramelization adds depth. If you scrape the pan with a little milk or broth and stir that into the eggs it picks up all the browned bits.

3) Cleaner slices and easy lift out: line the crock with foil to make a sling or spray/butter it well, then let the finished bake rest 10 to 15 minutes before cutting. Also save a handful of cheese to sprinkle on top the last 15 minutes so it browns nicely instead of burning.

4) Make ahead and reheat smart: assemble the night before so everything soaks evenly, or freeze portions for quick breakfasts later. Reheat in the oven or toaster oven to keep edges crisp, the microwave makes it sort of rubbery.