Low-Carb Zucchini Parmesan Casserole

Comforting, cheesy, and surprisingly light, this Low-Carb Zucchini Parmesan Casserole turns an overabundance of summer zucchini (or frozen rounds in winter) into a satisfying low-carb main or side. It’s the kind of recipe that fits weeknight schedules: quick to assemble, forgiving in the oven, and easy to adapt—add shredded rotisserie chicken for extra protein or keep it vegetarian for meatless nights.

Ingredients

½×1×2×3×4×5×6×7×8×9×10×

ⓘ Original recipe (1×) yields 6 servings

• 4 medium zucchini (about 1.8 lb / 800 g), trimmed and sliced into 1/4-inch rounds
• 1 small yellow onion, finely chopped (about 3/4 cup)
• 2 tablespoons extra-virgin olive oil, divided
• 3 large eggs, lightly beaten
• 2 cups shredded part-skim mozzarella (about 8 oz / 225 g)
• 1/2 cup finely grated Parmesan (about 50 g)
• 1/3 cup almond flour (about 35 g)
• 2 cloves garlic, minced
• 1 teaspoon dried oregano
• 1/2 teaspoon dried basil or 1 tablespoon chopped fresh basil
• 1/2 teaspoon salt (adjust to taste)
• 1/4 teaspoon black pepper
• Optional: 2 cups shredded rotisserie chicken (about 300 g) to make it higher-protein
• Optional garnish: chopped fresh parsley or a pinch of red pepper flakes

Instructions

1. Preheat the oven to 375°F (190°C). Grease a 9x13-inch (or similar) baking dish with 1 teaspoon olive oil or nonstick spray.
2. Warm 1 tablespoon olive oil in a skillet over medium heat. Add the chopped onion and a pinch of salt; cook, stirring occasionally, until translucent, about 5–6 minutes. Add minced garlic and cook 30 seconds more. Remove from heat and let cool slightly.
3. While the onion cools, trim and slice the zucchini into 1/4-inch rounds. If zucchini are very watery, sprinkle with 1/2 teaspoon salt, place in a colander for 10 minutes, then pat dry with paper towels to reduce excess moisture.
4. In a large bowl, whisk the eggs. Next, stir in the cooked onion and garlic, almond flour, dried oregano, dried basil (if using), salt, pepper, half the mozzarella (1 cup), and half the Parmesan (1/4 cup). If using rotisserie chicken, fold it in now.
5. Fold the zucchini slices gently into the egg-cheese mixture, coating evenly. Transfer half of the mixture into the prepared baking dish, spreading it into an even layer.
6. Sprinkle the remaining mozzarella and Parmesan evenly over the first layer. Then top with the remaining zucchini mixture and press down lightly so the casserole holds together.
7. Drizzle the remaining 1 tablespoon olive oil evenly over the top. Bake uncovered until the top is golden and set and a knife inserted near the center comes out clean, 30–40 minutes (longer if you added chicken or if the zucchini were not patted dry).
8. Let the casserole rest 8–10 minutes before slicing. Garnish with chopped parsley or red pepper flakes if desired, and serve warm.

Low-Carb Zucchini Parmesan Casserole — Notes & Variations

• To make individual portions, divide the mixture into 6 or 8 ovenproof ramekins; reduce bake time to 20–28 minutes.
• For a chewier top, switch half the mozzarella to provolone or a low-moisture cheddar.
• Make it meat-free: omit the rotisserie chicken and add 1/2 cup chopped sun-dried tomatoes (not oil-packed) or 1/2 cup canned garbanzo beans rinsed and patted dry for extra texture (note: garbanzos raise carbs).

Recipe Details

• Prep time: 15 minutes (plus optional 10 minutes to drain zucchini)
• Cook time: 30–40 minutes
• Total time: 45–65 minutes
• Yield: 6 servings
• Category: Main dish or side
• Cuisine: American / Low-carb

Nutrition Facts

Estimated nutrition per serving

Calories~280 kcal

% Daily Value*

Total Fat

~20 g

Protein

~17 g

Total Carbohydrate

~7 g

Dietary Fiber

~1–2 g

Substitutions

• Almond flour: substitute 1/3 cup ground pork rinds for even fewer carbs, or 1/4 cup coconut flour (absorbent; add an extra egg).
• Mozzarella: swap for Monterey Jack, provolone, or a sharp cheddar for stronger flavor.
• Parmesan: Pecorino Romano can be used for saltier, tangier notes.
• Herbs: use 1 teaspoon Italian seasoning instead of individual dried herbs, or 2 tablespoons fresh basil/parsley.
• Chicken: use leftover cooked chicken breast or turkey; do not use canned chicken.

Storage and Reheating

• Refrigerator: Store tightly covered for 3–4 days. Reheat single slices in a 350°F (175°C) oven for 10–12 minutes or in the microwave for 60–90 seconds.
• Freezer: Freeze portions in airtight containers for up to 3 months. Thaw overnight in the fridge and reheat in a 350°F oven for 20–25 minutes until warmed through.
• To retain texture: reheat in the oven or a toaster oven rather than microwaving when possible; this helps the top re-crisp.

FAQs

• Can I use yellow squash instead of zucchini? Yes—use the same volume of sliced yellow squash as a straight swap.
• Is this casserole keto-friendly? Yes, as written (without garbanzo beans) it is low in net carbs and fits many low-carb and keto meal plans; check ingredient brands for exact carb counts.
• Can I prepare this ahead? Assemble in the baking dish, cover, and refrigerate up to 24 hours before baking; add a few extra minutes to cook time if very cold.
• Why did my casserole release liquid? Zucchini contain water—salting and draining slices before mixing reduces excess moisture.

Whether you’re trimming a summer harvest or using packaged frozen zucchini rounds, this Low-Carb Zucchini Parmesan Casserole streamlines comfort food into a lighter, flavorful dish that adapts easily to what’s in your fridge. Try it as a weeknight main or double it for potlucks.

For more low-carb dinner ideas and vegetable-forward recipes, visit The Nutrient recipe index for inspiration and meal-planning tips.