Name: Low Carb Zucchini and Sausage Casserole
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Ingredients: 3 medium zucchini, sliced into 1/4-inch half moons; 1 pound Italian sausage, casings removed; 1 small yellow onion, finely chopped; 3 cloves garlic, minced; 1 cup low sugar marinara sauce or crushed tomatoes; 1 1/2 cups shredded mozzarella cheese; 1/2 cup grated Parmesan cheese; 2 large eggs; 1/3 cup heavy cream; 1–2 tablespoons olive oil or avocado oil; 1 teaspoon Italian seasoning; 1/2 teaspoon crushed red pepper flakes; 1/2 teaspoon kosher salt, plus more to taste; 1/4 teaspoon black pepper; 1/2 cup chopped bell pepper; 1/2 cup sliced mushrooms; 1/4 cup chopped fresh basil or parsley; 1/2 cup ricotta or cottage cheese

Low Carb Zucchini and Sausage Casserole tastes rich, cheesy, and savory with just enough freshness from the zucchini to keep it from feeling heavy. It works perfectly for busy weeknights, meal prep, or anyone who wants comfort food on the table in about 45 minutes without a carb coma. I tested this on my own family of picky Midwestern eaters, and not a single person asked, "Where are the noodles?"

Why Make This Low Carb Zucchini and Sausage Casserole at Home

You control the ingredients, so this casserole stays low carb without weird fillers or mystery starches. You choose the sausage, the cheese, and the level of spice, and you skip the sugar that many store bought sauces sneak in.

This recipe also uses simple prep and one main baking dish, so cleanup stays painless. You can prep it ahead, bake it later, and feed a crowd without hovering over the stove.

My whole family devoured this Low Carb Zucchini and Sausage Casserole and asked for seconds, even the carb lovers ★★★★★

Ingredients You Need

Main ingredients

Zucchini:
- 3 medium zucchini, sliced into half moons, about 1/4 inch thick
- Choose firm zucchini with shiny skin and no soft spots.
- If the zucchini feels huge and seedy, scoop out the center so the casserole does not turn watery.
Sausage:
- 1 pound Italian sausage, casings removed
- Use mild or hot Italian sausage based on your spice tolerance.
- Choose pork sausage for the best flavor, or use chicken or turkey sausage for a lighter option.
Onion and garlic:
- 1 small yellow onion, finely chopped
- 3 cloves garlic, minced
- You can use 1 teaspoon garlic powder and 1 teaspoon onion powder in a pinch, but fresh gives better flavor.
Low carb tomato base:
- 1 cup low sugar marinara sauce or crushed tomatoes
- Look for brands with 5 grams of net carbs or less per half cup and no added sugar.
- Rao’s, Yo Mama’s, or a store brand labeled “no sugar added” usually works well.
Cheese:
- 1 1/2 cups shredded mozzarella cheese
- 1/2 cup grated Parmesan cheese
- Shred your own cheese if possible, since bagged shreds often contain starch that adds carbs and affects melting.
Eggs and cream:
- 2 large eggs
- 1/3 cup heavy cream
- This mixture binds the casserole and gives it a quiche style custard texture without tasting eggy.
Oil and seasonings:
- 1 to 2 tablespoons olive oil or avocado oil
- 1 teaspoon Italian seasoning
- 1/2 teaspoon crushed red pepper flakes, optional
- 1/2 teaspoon kosher salt, plus more to taste
- 1/4 teaspoon black pepper

Optional add ins

1/2 cup chopped bell pepper for extra crunch and color
1/2 cup sliced mushrooms for more umami flavor
1/4 cup chopped fresh basil or parsley for a fresh finish
1/2 cup ricotta or cottage cheese for a creamier, lasagna style texture

Pantry shortcuts and notes

Use pre sliced zucchini from the produce section if you feel short on time, but pat it dry before cooking.
Use pre shredded mozzarella and pre grated Parmesan if that fits your schedule, but expect slightly less melty cheese.
Use jarred low carb marinara to save time instead of simmering your own sauce.
Keep bulk Italian sausage in the freezer, portioned in 1 pound bags, so you can pull it out for quick casseroles.

Equipment list

9 by 13 inch baking dish or similar size casserole dish
Large skillet for browning sausage and vegetables
Cutting board and sharp knife
Mixing bowl and whisk
Wooden spoon or spatula
Colander or clean kitchen towel to drain zucchini
Aluminum foil to cover the casserole if the top browns too quickly

Tips & Mistakes

Salt the zucchini slices lightly and let them sit 10 to 15 minutes, then pat dry, so the casserole does not turn watery.
Slice zucchini evenly so it cooks at the same rate and does not turn mushy in some spots and crunchy in others.
Brown the sausage until it gets deep color, since that browning builds flavor and keeps the casserole from tasting flat.
Drain excess grease from the sausage so the finished dish tastes rich but not greasy.
Use a low sugar marinara and read labels, since many sauces hide sugar that raises the carb count.
Do not overbake, since extra time in the oven can dry out the sausage and turn the zucchini to mush.
Let the casserole rest 10 minutes before slicing so it sets up and cuts cleanly instead of sliding all over the plate.
Taste the sausage mixture before baking and adjust salt and spice, since bland filling leads to bland casserole.
Shred cheese from a block when possible, since it melts smoother and gives a better cheesy pull.
Grease the baking dish lightly so the casserole releases easily and cleanup stays simple.

How to Make Low Carb Zucchini and Sausage Casserole

Step 1: Prep the zucchini

Slice the zucchini into half moons about 1/4 inch thick. Sprinkle the slices with a light layer of salt and place them in a colander over the sink. Let them sit 10 to 15 minutes so they release some moisture, then pat them very dry with paper towels or a clean kitchen towel.

Step 2: Brown the sausage and aromatics

Heat a large skillet over medium high heat and add the oil. Add the sausage and break it into crumbles with a spatula while it cooks. Stir in the chopped onion and cook until the sausage browns and the onion softens, about 6 to 8 minutes.

Add the garlic, Italian seasoning, crushed red pepper flakes, salt, and black pepper. Stir and cook 1 to 2 minutes until the garlic smells fragrant. Taste a small piece and adjust salt or spice if needed.

Step 3: Add the tomato base

Pour the low sugar marinara or crushed tomatoes into the skillet with the sausage mixture. Stir to combine and let it simmer 3 to 5 minutes so the flavors meld and the sauce thickens slightly. Turn off the heat and set the skillet aside.

Step 4: Make the egg and cream mixture

Crack the eggs into a mixing bowl and whisk until smooth. Add the heavy cream and whisk again until the mixture looks uniform. Stir in a small pinch of salt and pepper.

Step 5: Assemble the casserole

Preheat your oven to 375 degrees Fahrenheit. Lightly grease the baking dish with oil or cooking spray. Spread half of the zucchini slices in an even layer on the bottom of the dish.

Spoon half of the sausage and tomato mixture over the zucchini and spread it out. Sprinkle with half of the mozzarella and half of the Parmesan. Repeat with the remaining zucchini, sausage mixture, and cheeses to form a second layer.

Pour the egg and cream mixture evenly over the top, tilting the dish slightly if needed so it seeps down into the layers. If you use ricotta or cottage cheese, dollop it between the layers before you add the final cheese topping. Place the baking dish on a sheet pan if you worry about any bubbling over.

Step 6: Bake

Place the casserole in the oven and bake for 25 to 30 minutes. Check at the 20 minute mark, and if the top browns too quickly, tent it loosely with foil. The casserole finishes when the cheese turns golden in spots and the edges bubble.

Step 7: Rest and serve

Remove the casserole from the oven and let it rest 10 minutes on the counter. This rest time helps the egg and cream mixture set so you get neat slices. Cut into squares and serve hot, with extra grated Parmesan and fresh herbs on top if you like.

Variations I've Tried

I swapped Italian sausage for spicy chorizo and used a Mexican blend cheese with a sprinkle of cumin and chili powder, and the casserole tasted like a low carb taco bake. I tried a chicken sausage version with spinach, mushrooms, and a little feta, which gave the dish a lighter, Mediterranean vibe. I also tested a white sauce version with Alfredo style low carb sauce instead of tomato, and it turned into a super rich, almost keto mac and cheese substitute.

I made a vegetarian version with plant based sausage and extra mushrooms, and it still delivered great flavor and texture. I tried layering thin slices of yellow squash with the zucchini for more color, and that worked well as long as I salted and dried both. I also tested baking it in individual ramekins for portion control, which made it perfect for meal prep lunches.

How to Serve Low Carb Zucchini and Sausage Casserole

Serve this Low Carb Zucchini and Sausage Casserole with a simple green salad, some sliced cucumbers, or a side of steamed broccoli to keep the plate low carb and colorful. Add a side of cauliflower rice or mashed cauliflower if you want something that feels like a starchy side without the carbs. Kids often like a side of garlic bread or toast, so you can keep their plates flexible while you stay low carb. Pair it with iced tea, sparkling water, or flavored water for an easy family friendly meal.

How to store

Fridge: Let the casserole cool to room temperature, then cover the dish tightly or transfer slices to airtight containers and refrigerate for up to 4 days.
Freezer: Wrap individual portions tightly in plastic wrap, then place them in a freezer bag or container and freeze for up to 2 months.
Reheat in oven: Place slices in an oven safe dish, cover loosely with foil, and warm at 350 degrees Fahrenheit for 15 to 20 minutes until hot in the center.
Reheat in microwave: Heat a slice on a microwave safe plate at 50 to 70 percent power in 45 to 60 second bursts until hot, and let it sit 1 minute so the heat distributes evenly.