Easy Make-Ahead Keto Breakfast Casserole

If you need a hot breakfast that keeps you full for hours without any mid-morning carb crash, this keto breakfast casserole is the answer. It’s a cheesy, sausage-studded bake that tastes indulgent but fits a low-carb lifestyle perfectly.

Make it the night before and just slide it into the oven when you wake up. The rich custard, savory sausage, and tender spinach come together in a dish that feels special enough for brunch but easy enough for a weekday.

Why This Casserole Stays in My Rotation

The texture hits every note you want: a set, creamy egg layer with pockets of melted cheddar and crisp-edged sausage. I love that I can prep it in 15 minutes and forget about it until I smell the cheese browning.

Leftovers reheat beautifully and stay just as satisfying, which means I often make it on Sunday and eat well all week.

Ingredients

• 1 lb bulk pork sausage: look for one with no added sugar for keto
• 8 oz fresh baby spinach: roughly chopped
• 12 large eggs
• 1 cup heavy cream: this makes the custard rich and fluffy
• 2 cups shredded sharp cheddar cheese: freshly shredded melts best, but pre-shredded works
• 1/2 cup chopped green onions: plus extra for garnish
• 1 tsp garlic powder
• 1/2 tsp fine sea salt
• 1/4 tsp black pepper
• Butter or oil: for greasing the pan

Variations / Substitutions

• Swap the sausage: use sugar-free bacon, cooked and crumbled, or spicy Italian sausage for heat.
• Go dairy-free: replace heavy cream with full-fat canned coconut cream and use a meltable dairy-free cheese.
• Change the greens: wilted kale or chopped bell peppers work, though peppers will add a couple extra carbs.

If this casserole becomes a staple, you might also love our Keto Sausage Balls for a grab-and-go breakfast.

How To Make Keto Breakfast Casserole

Step 1: Brown the Sausage and Wilt the Spinach

In a large skillet over medium-high heat, cook the 1 lb sausage until browned and cooked through, about 6 to 8 minutes, breaking it into crumbles. Add the 8 oz spinach in handfuls and cook, stirring, until just wilted, about 2 minutes.

Take the pan off the heat and transfer the mixture to a colander set in the sink. Press firmly with the back of a spoon to squeeze out as much liquid as you can, this keeps the casserole from turning watery.

Step 2: Whisk the Egg Mixture

While the sausage cools slightly, crack the 12 eggs into a large bowl. Pour in the 1 cup heavy cream, then add the 1 tsp garlic powder, 1/2 tsp salt, and 1/4 tsp pepper.

Whisk until everything is smooth and the eggs are frothy, about 30 seconds. You should see tiny bubbles on the surface, that means air is incorporated, which helps the casserole puff up slightly as it bakes.

Step 3: Assemble the Casserole

Preheat the oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter or oil. Spread the sausage-spinach mixture evenly across the bottom, then sprinkle 1 1/2 cups of the shredded cheddar on top. Scatter the 1/2 cup green onions over the cheese.

Pause and make sure the mixture is arranged in an even layer so every bite gets a good mix. Pour the egg mixture slowly over everything, letting it seep into the gaps.

Step 4: Bake Until Golden and Serve

Top with the remaining 1/2 cup cheddar and bake for 35 to 40 minutes. The casserole is done when the center jiggles only slightly and the edges have pulled away from the sides.

Slide it out of the oven and let it sit for 5 minutes so the slices hold together. Cut into 8 squares and serve warm, straight from the dish, with a scatter of extra green onions on top.

Tips for the Best Keto Casserole

• Use freshly shredded cheese for the creamiest melt. The anti-caking agents in pre-shredded can make it grainy.
• To get clean slices, let the casserole rest a full 10 minutes after baking before cutting.
• For a spicy kick, mix a diced jalapeño into the sausage or use pepper jack cheese.
• If you’re prepping ahead, assemble the entire casserole without baking, cover, and refrigerate overnight. Add 5 to 10 minutes to the bake time.

Bake times for different pans:

Storing and Reheating Leftovers

• Refrigerate: Store cooled slices in an airtight container for up to 4 days.
• Reheating: Warm individual portions in the microwave for 60 to 90 seconds, or place slices in a 325°F oven for 10 minutes until heated through.

What To Serve With This Casserole

Because this dish is so hearty, a bright side helps balance it out. A handful of peppery arugula dressed with lemon juice and olive oil cuts through the richness perfectly. Sliced avocado with a pinch of salt is another no-cook option that adds creaminess and healthy fats.

Frequently Asked Questions

Can I use frozen spinach?

Yes, thaw a 10-ounce package and squeeze it completely dry before adding to the sausage. Excess moisture is the top reason casseroles turn out watery.

Can I make this dairy-free?

Replace the heavy cream with full-fat coconut cream and use a good-quality dairy-free cheddar. The texture will be slightly softer but still holds together.

Is this casserole gluten-free?

It is naturally gluten-free because no flour or bread is used, making it a safe choice for anyone avoiding gluten.

What cheese works best besides cheddar?

Any melting cheese will do: Monterey Jack keeps it mild, pepper jack adds heat, or smoked gouda brings a deeper, smokier flavor.

Keto Breakfast Casserole Recipe

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 40 minutes mins

Total Time 55 minutes mins

Servings: 8 servings

Calories: 480

Ingredients Method Notes

Ingredients

  

• 1 lb bulk pork sausage
• 8 oz fresh baby spinach
• 12 large eggs
• 1 cup heavy cream
• 2 cups shredded sharp cheddar cheese
• 1/2 cup chopped green onions
• 1 tsp garlic powder
• 1/2 tsp fine sea salt
• 1/4 tsp black pepper
• Butter or oil, for greasing

Method

 

1. In a large skillet over medium-high, cook sausage until browned, 6-8 min. Add spinach and wilt, about 2 min. Drain and squeeze out excess liquid.
2. Whisk eggs, heavy cream, garlic powder, salt, and pepper until frothy.
3. Preheat oven to 375°F (190°C). Grease a 9×13-inch dish. Layer sausage mixture, 1 1/2 cups cheese, and green onions. Pour egg mixture over top and sprinkle with remaining cheese.
4. Bake 35-40 minutes until center barely jiggles. Let rest 5 minutes, then slice and serve.

Notes

Letting the casserole rest a full 10 minutes after baking gives you the cleanest slices. Assemble it the night before, cover, and refrigerate; the flavors meld overnight and you just bake it in the morning, adding 5-10 minutes to the time.