Cheesy Zucchini Casserole (Zucchini Gratin)

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This easy, cheesy baked zucchini casserole recipe is perfect for using extra summer produce! Also called zucchini gratin, this dish uses simple ingredients and only takes 10 minutes of hands-on effort. And just like yellow squash casserole, it creates tender slices in a rich, creamy sauce.

As we head into August, I know I’m not the only one with more zucchini than I know what to do with. Even though I don’t have a garden, I still have a zucchini problem: I just couldn’t resist buying way too much at the farmers’ market. Well, zucchini casserole recipes are the perfect way to use up a lot of it at once!

The only thing is, I struggled with the name for this dish. Cheesy zucchini gratin? Baked zucchini casserole? Healthy zucchini bake? I couldn’t decide, so I’m using the names interchangeably.

If you still have leftover veggies, try more zucchini recipes next, like zucchini fries, zucchini chips, or zucchini noodle salad.

Ingredients & Substitutions

This section explains how to choose the best ingredients for zucchini squash casserole, what each one does in the recipe, and substitution options. For measurements, see the recipe card below.

• Zucchini – Use 3 medium zucchini with firm flesh and no nicks. Yellow squash would work equally well if that’s what you have on hand. Either way, slice the summer squash into thin rounds.
• Salt & Pepper
• Swiss Gruyere Shredded Cheese – I used a pre-mixed shredded blend, but you can also shred Swiss and Gruyere cheese separately yourself and mix them together. Alternatively, any shredded sharp cheese, such as cheddar cheese, will work as well. Harder cheeses, like parmesan cheese, might not melt as smoothly.
• Brie Cheese – Helps the sauce thicken and get creamy. You could also substitute cream cheese instead.
• Heavy Cream – Thins out the sauce, but not too much. I recommend using cream for the thickest sauce possible. Milk, half and half, almond milk, or coconut milk can work, but you’d need to use less so that the dish doesn’t get too watery.
• Butter – Adds richness to the sauce. I use grass-fed butter, but any unsalted variety will work.
• Garlic – Use minced or crushed, fresh or from a jar.
• Italian Seasoning – Use a store-bought mix or make homemade Italian seasoning in minutes.

VARIATION: Add onion!

You can saute some diced onions (or shallots), and stir them into the cheese sauce mixture, or slice the onion into rings and layer them with the zucchini slices.

How To Make Cheesy Baked Zucchini Casserole

This section shows how to make zucchini gratin, with step-by-step photos and details about the technique, to help you visualize it. For full instructions, including amounts and temperatures, see the recipe card below.

1. Drain zucchini. Place the zucchini slices in a colander, sprinkle generously with salt (3/4 teaspoon salt is a good amount), and drain over the sink for 45 minutes. (Doing this prevents a watery casserole!) Pat dry.
2. Arrange. Arrange the zucchini slices in rows in a baking dish, sprinkling half of the shredded cheese between each row. Season with pepper. (No salt needed here, as we already salted the slices in step 1.)

3. Make sauce. Heat brie, cream, butter, and garlic in a saucepan over medium-low heat. Stir frequently, until cheese melts and sauce is smooth. (Alternatively, you can heat the ingredients in a bowl in the microwave and stir every 20-30 seconds, until melted.) Add salt to taste. Pour the sauce evenly over the zucchini in the baking dish.

4. Add more cheese. Sprinkle more shredded cheese on top, followed by Italian seasoning.
5. Bake. Place the zucchini casserole in the oven, until the zucchini is soft and the cheese on top is dark golden brown.

Tips For The Best Zucchini Casserole

To make sure your au gratin zucchini turns out perfect, keep these tips in mind.

• Don’t skip the salting and draining step. Otherwise this recipe for zucchini casserole will stay too watery, because the zucchini will release water as it cooks. Salting beforehand removes some of the water in advance.
• Try different cheeses (or herbs). Fresh herbs such as rosemary would also taste delicious with this baked zucchini casserole recipe.
• If sauce stays watery, bake longer. Cover the top of the casserole, lower the temperature to 350 degrees F, and bake for 10-20 minutes more, until the sauce thickens.
• Add a crunchy topping, if desired. Use panko bread crumbs if you want, or crushed pork rinds for a low carb alternative.

Storage Instructions

Cover leftovers in an airtight container and store in the refrigerator for up to 3 days.

Can You Freeze Zucchini Casserole?

Avoid freezing this zucchini casserole recipe, as the texture will change too much after thawing.

Reheating Instructions:

Heat in a microwave or 350 degree F oven until warm.

What To Serve With Zucchini Casserole

This dish pairs well with most proteins, but especially Italian dishes! Try these mains:

Baked Basil Pesto Chicken

Pan Seared Pork Chops

Easy Keto Meatballs

Creamy Tuscan Salmon

More Cheesy Veggie Casserole Recipes

If you like a baked zucchini casserole recipe, you’ll enjoy these cheesy favorites too!

Pesto Chicken Cauliflower Casserole

Broccoli Cheese Casserole

Brussels Sprouts Casserole

Loaded Cauliflower Casserole

4.8 from 53 votes

Cheesy Zucchini Casserole (Zucchini Gratin)

This easy zucchini gratin recipe is a baked cheesy zucchini casserole that everyone will love! Only 10 minutes prep time & simple ingredients.

Prep: 10 minutes

Cook: 30 minutes

Total: 1 hour 25 minutes

Author: Maya Krampf from WholesomeYum.com

Servings: 6 (adjust to scale recipe)

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Ingredients

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• 3 medium Zucchini (sliced in 1/4" thick slices) ▢
• 3/4 tsp Sea salt ▢
• 1 1/2 cup Swiss Gruyere shredded cheese blend (or any shredded sharp cheese; divided) ▢
• 1/4 tsp Black pepper ▢
• 3 oz Brie cheese (edges cut off) ▢
• 1/3 cup Heavy cream ▢
• 1 tbsp Unsalted butter ▢
• 2 cloves Garlic (minced or crushed) ▢
• 1/2 tbsp Italian seasoning ▢

Instructions

Tap on the times in the instructions below to start a kitchen timer while you cook.

1. Toss the zucchini slices with sea salt. Place into a colander and set over the sink to drain for 45 minutes. Pat dry at the end.

2. Preheat the oven to 400 degrees F (204 degrees C).

3. In a small 1.5 quart (1.5 L) casserole dish, arrange the zucchini slices in several overlapping rows, sprinkle lightly with shredded cheese. Add another row and more shredded cheese. Continue alternating zucchini and cheese until you fill the entire baking dish. You’ll use about 3/4 cup (half of the total) cheese altogether. Season lightly with black pepper.

4. Combine the brie, cream, butter, and garlic in a small saucepan. Heat for a few minutes on the stove over low to medium-low heat, stirring frequently, until the cheese melts and the mixture is smooth. If desired, add sea salt to taste. Pour the mixture evenly over the zucchini.

5. Sprinkle the remaining 3/4 cup shredded cheese blend on top. Top with Italian seasoning.

6. Bake for about 20-25 minutes, until the cheese on top is dark golden brown and the zucchini is soft.

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Recipe Notes

Serving size: 1/6 of entire pan

Nutrition Facts

Amount per serving. Serving size in recipe notes above.

Calories 235

Fat 19.3g

Protein 11.9g

Total Carbs 4.5g

Net Carbs 3.3g

Fiber 1.2g

Sugar 2.9g

Nutrition facts are provided as a courtesy. Have questions about calculations or why you got a different result? Please see our nutrition policy.

Course: Side Dish

Cuisine: American

Keywords: baked zucchini casserole, zucchini casserole, zucchini casserole recipe, zucchini gratin

Calories: 235 kcal

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