Keto Zucchini Casserole

This easy, baked Keto Zucchini Casserole with cheese and sour cream is the best keto vegetarian meal or side dish. Plus, this healthy zucchini gratin is egg-free and gluten-free. The best keto casserole recipe for using all your summer zucchini.

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A keto zucchini casserole is a low-carb casserole made with a cheesy wheat-free white sauce. In fact, most regular zucchini casseroles use a combination of milk, flour, and butter to create a thick white sauce.

However, milk and flour are not keto-friendly. Milk contains a lot of carbs and sugar from lactose, and flour is a high-carb ingredient.

So, the trick to achieving a similar texture is to make your zucchini casserole with sour cream, cream, and shredded hard cheese.

Ingredients and Substitutions

Let’s see the simple ingredients to make your casserole flavorsome:

• Zucchini – See next paragraph on how to prepare zucchini to make the best zucchini casserole. Zucchini are great keto-friendly vegetables with very low net carbs!
• Onion – fried onion is my French twist to this zucchini gratin! Soft, butter-fried onions are a delicious addition to the zucchini. However, you can skip them if you are not a fan of onions or can’t digest them very well.
• Garlic
• Salt
• Heavy cream – is a great keto-friendly dairy product with only 2.8 grams of carbs per 100 grams.
• Sour cream – sour cream is keto-friendly. It’s regular cream, just fermented with lactic acid bacteria resulting in a naturally sour cream perfect for thickening your keto sauce.
• Grated parmesan – the best cheese to add a strong cheesy, salty flavor to any gratin.
• Grated hard mozzarella – if you love strings in your sauce, mozzarella is the best choice.

How To Make Keto Zucchini Casserole

1. Prep the Zucchini: Zucchini is 95% water, so removing excess moisture is crucial. Slice zucchini with skin on.
2. Toss slices with 1 teaspoon of salt in a bowl.
3. Let sit for 20 minutes to extract water. Drain and pat dry with paper towels.
4. Choose the Right Baking Dish: Consider volume, not just length. Use a 1.5-liter (50-fluid-ounce or 6-cup) glass pan. Square dishes work best for even zucchini arrangement.
5. Arrange Zucchini Properly: Lay slices in single, overlapping rows. Avoid multiple layers to ensure even cooking.
6. Apply Cheese Sauce Correctly: Use a thick, creamy sauce made with sour cream. Spread evenly with a spatula or spoon for consistent flavor.
7. Add Cheese Topping: For a keto version, be generous with cheese. Adjust amount to personal preference.
8. Bake Carefully: Bake for only 15-20 minutes to prevent mushiness. Casserole is done when cheese is broiled on top, bubbles form on the sides, and zucchini is soft but still tender (use knife test).

Expert Tips

1. Zucchini selection: Choose firm, medium-sized zucchini for best results. Overly large zucchini can be watery and less flavorful.
2. Uniform slicing: Use a mandoline slicer for even zucchini slices, ensuring consistent cooking throughout the dish.
3. Salt alternative: If you’re watching sodium intake, you can use a salt-free seasoning blend to extract moisture from the zucchini.
4. Cheese variations: Experiment with different cheese combinations like Gruyère, fontina, or smoked gouda for unique flavor profiles.
5. Adding Herbs: Add fresh herbs like thyme, basil, or oregano to the cheese sauce for an extra layer of flavor.
6. Crispy Topping: For added texture, mix some crushed pork rinds or almond flour with grated Parmesan and sprinkle on top before baking.
7. Make-ahead option: Prepare the casserole up to the point of baking, cover, and refrigerate for up to 24 hours before baking.
8. Leftover tip: Leftover casserole can be reheated in a skillet to crisp up the bottom for a delicious next-day meal.
9. Vegetable variation: Try mixing in other low-carb vegetables like bell peppers or spinach for added nutrition and color.
10. Protein boost: For a heartier meal, add cooked, crumbled bacon or shredded rotisserie chicken to the cheese sauce.

More Keto Zucchini Recipes

Below I listed my best low carb casserole recipes for you to try

Zucchini Pizza Casserole

Zucchini Omelette

Zucchini Sausage Casserole

Zucchini Noodles With Pesto

Did You Like This Recipe?

Leave a comment below or head to our Facebook page for tips, our Instagram page for inspiration, our Pinterest for saving recipes, and Flipboard to get all the new ones!

Keto Zucchini Casserole

6.6gNet Carbs

This Keto Zucchini Casserole is a cheesy keto dinner or side dish full of healthy low-carb vegetables and sour cream for only 6.6g of net carbs.

Author: Carine Claudepierre

Prep: 30 minutes mins

Cook: 15 minutes mins

Total: 45 minutes mins

Yield: 6 servings

Serving Size: 1 serving

4.64 from 162 votes

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Ingredients

US Customary – Metric

• ▢ 2 pounds Zucchini 4 large zucchini
• ▢ 1 teaspoon Salt
• ▢ 2 tablespoons Unsalted Butter melted or olive oil + 1 tablespoon to grease dish
• ▢ 2 oz Onion peeled, sliced
• ▢ 3 Garlic Clove
• ▢ ½ cup Heavy Cream
• ▢ ½ cup Sour Cream
• ▢ 1 cup Shredded Parmesan divided
• ▢ 1 cup Grated Mozzarella divided (or old mature cheddar or Emmental)
• ▢ 1 teaspoon Salt

Instructions

• Preheat the oven to 425°F (220°C). Grease a 1.5-liter square glass or ceramic baking dish with butter. Set aside.
• Slice the zucchini into 1/4 inch thick (0.6 cm), place them on a large bowl, sprinkle 1 teaspoon salt all over the slices and toss with your hands to bring the salt in contact with all slices. Set aside 20 minutes. This step will extract the zucchini water and prevent a watery casserole, don't skip!
• Drain the zucchini slices, then lay them onto absorbent paper and pat dry with more absorbent paper to remove as much excess water as you can.
• In a large saucepan, melt butter over medium heat and fry onions until fragrant and soft. Stir in garlic, pour heavy cream, sour cream, and keep cooking until it forms bubbles on the sides.
• Stir in half of the grated parmesan and half of the grated mozzarella until the cheese is fully melted and forms a cheesy sauce.
• Lay the zucchini slices in a row into the square baking dish. See the picture in my post or watch the video to see how to make this.
• Pour the cheese sauce and top of the zucchini and spread evenly to cover all the zucchini slices. Sprinkle the rest of the parmesan and mozzarella cheese all over the zucchini slices.
• Bake for 15–20 minutes or until cheese is broiled on top, the sauce bubbles in the pan, and zucchini are tender. Don't overbake, or the zucchini will become mushy.

Notes

Storage: Store in the fridge in an airtight container for up to 4 days. Rewarm in a saucepan or the microwave. Freeze in a single-serve airtight container for easy single meal serve. Defrost in the fridge the day before and reheat it in the microwave or saucepan.

Tools

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NutritionServing Size: 1 serving

Yield: 6 servings

Nutrition

Serving: 1 servingCalories: 298.4 kcal (15%)Carbohydrates: 8.3 g (3%)Fiber: 1.7 g (7%)Net Carbs: 6.6 gProtein: 13.4 g (27%)Fat: 24.3 g (37%)Saturated Fat: 14.6 g (91%)Cholesterol: 76.6 mg (26%)Sodium: 1216 mg (53%)Potassium: 491.4 mg (14%)Sugar: 5.1 g (6%)Vitamin A: 1100.3 IU (22%)Vitamin C: 28.4 mg (34%)Calcium: 342.2 mg (34%)Iron: 0.8 mg (4%)