🥒🧀 Keto Zucchini Casserole

This creamy, cheesy zucchini casserole makes an excellent low-carb side dish or vegetarian dinner. The zucchini is layered with a rich sauce made from onion, garlic, heavy cream, sour cream, Parmesan, and mozzarella, then baked until bubbling and golden. The original recipe yields 6 servings and lists 6.6 g net carbs per serving.

🛒 Ingredients

  • 2 lb (about 4 large) zucchini
  • 1 teaspoon salt, for drawing moisture from the zucchini
  • 2 tablespoons unsalted butter, melted
  • 1 tablespoon butter or olive oil, for greasing the baking dish
  • 2 oz onion, peeled and sliced
  • 3 garlic cloves, minced
  • ½ cup heavy cream
  • ½ cup sour cream
  • 1 cup shredded Parmesan cheese, divided
  • 1 cup grated mozzarella cheese, divided
  • Additional salt, to taste

The original recipe also notes that mozzarella can be replaced with mature cheddar or Emmental.

👩‍🍳 Detailed Instructions

1. Preheat the oven

Preheat your oven to 425°F (220°C).

Grease a 1.5-liter square glass or ceramic baking dish with butter or olive oil and set it aside.

2. Slice the zucchini

Wash and dry the zucchini. Slice it into approximately ¼-inch (0.6 cm) rounds.

Try to keep the slices relatively uniform in thickness so they cook evenly.

3. Remove excess moisture — don’t skip this step

Place the zucchini slices in a large bowl and sprinkle them with 1 teaspoon salt.

Toss thoroughly with your hands so the salt comes into contact with all the slices.

Let the zucchini sit for 20 minutes. The salt draws out excess water, which is especially important because zucchini naturally contains a lot of moisture.

4. Dry the zucchini

After 20 minutes, drain the liquid released by the zucchini.

Spread the slices over absorbent paper towels and pat them thoroughly dry. Use additional paper towels to remove as much moisture as possible.

This is the key to avoiding a watery casserole.

5. Sauté the onion

Heat a large saucepan over medium heat and melt the 2 tablespoons butter.

Add the sliced onion and cook until it becomes soft and fragrant, stirring occasionally.

6. Add the garlic

Add the minced garlic and cook briefly, about 30–60 seconds, until fragrant.

Avoid browning the garlic too much, as burnt garlic can give the sauce a bitter flavor.

7. Make the creamy sauce

Pour in the heavy cream and sour cream.

Continue cooking over medium heat until the mixture becomes hot and small bubbles begin forming around the edges.

8. Add the first portion of cheese

Add ½ cup Parmesan and ½ cup mozzarella to the saucepan.

Stir continuously until the cheese melts completely and the mixture becomes a smooth, creamy cheese sauce.

9. Arrange the zucchini

Place the dried zucchini slices into the prepared baking dish.

Arrange them in overlapping rows so the slices are evenly distributed throughout the dish.

10. Add the cheese sauce

Pour the creamy cheese sauce evenly over the zucchini.

Use a spatula or the back of a spoon to spread the sauce so it reaches between and over the zucchini slices.

11. Add the remaining cheese

Sprinkle the remaining ½ cup Parmesan and ½ cup mozzarella evenly over the top.

This creates the golden, bubbly cheese crust as the casserole bakes.

12. Bake

Place the casserole in the preheated oven and bake for approximately 15–20 minutes.

It’s ready when:

  • The cheese is golden and lightly broiled on top
  • The sauce is bubbling around the edges
  • The zucchini is tender

Don’t overbake it. Overcooking can make the zucchini mushy and release additional water.

13. Rest before serving

Remove the casserole from the oven and let it rest for about 5 minutes before serving. This allows the creamy cheese sauce to settle slightly.

⭐ Tips for the Best Keto Zucchini Casserole

  • Dry the zucchini very well. This is the most important step for preventing watery casserole.
  • Don’t slice the zucchini too thin, or it can become mushy.
  • Use freshly shredded cheese when possible for a smoother sauce.
  • For extra flavor, add a pinch of black pepper, Italian seasoning, or red pepper flakes.
  • If you like a stronger garlic flavor, add another small clove.
  • For extra browning, place the casserole under the broiler for the final 1–2 minutes, watching it carefully.

🧊 Storage & Reheating

Store leftovers in an airtight container in the refrigerator for up to 4 days.

Reheat individual portions in the microwave or gently in a saucepan. The casserole can also be frozen in single-serving airtight containers; thaw overnight in the refrigerator before reheating.

📊 Nutrition

According to the original recipe, per serving (1 of 6):

  • Calories: 298.4
  • Total carbohydrates: 8.3 g
  • Fiber: 1.7 g
  • Net carbs: 6.6 g
  • Protein: 13.4 g
  • Fat: 24.3 g