Zucchini Gratin (Cheesy Scalloped Zucchini)

This zucchini gratin is an amazing side dish and a great way to use up lots of zucchini or summer squash. The zucchini is first browned in a pan then baked with a flavorful sauce and topped with bold-tasting cheese and crunchy breadcrumb and parmesan topping. I can not imagine zucchini ever tasting better!

Ingredients:

• Zucchini – I used a zucchini and summer squash mix just because green and yellow colors look prettier together. Feel free to use just zucchini or just summer squash for this recipe.
• Cheese – this is a really important ingredient of this dish. It takes it from 'it’s good’ to 'wow, this is amazing, what’s in it?!’. So I really encourage it to use bold-tasting cheese, like Gruyere cheese (this is what I used). Gruyere cheese is one of the best Swiss cheeses – it’s made from cow’s milk, it has a nutty, sharp taste and melts very well. Gruyere cheese can be unfortunately a little pricey so you could try to substitute it for American Swiss cheese/Emmental cheese. It’s important to choose cheese that melts easily. This website lists Jarlsberg cheese, Emmentaler cheese, Raclette cheese (this cheese probably melts too well for this recipe), Appenzeller cheese, Comte and Beaufort cheese as 5 best substitutes for Gruyere cheese. Here you can find more recipes using Gruyere cheese.
• If you don’t have Parmesan cheese on hand you can add more breadcrumbs, but the Parmesan adds lots of flavor to the dish. This crunchy breadcrumb-Parmesan topping is really amazing, it’s the same topping that I use to make this delicious chicken broccoli rice casserole.

Change it up:

• Make it more calorie-friendly: I must admit this recipe is not very calorie-friendly. There’s lots of cream, cheese, butter, more cheese, and breadcrumbs 😉 If you would like, you can reduce the amount of the sauce a little, add half the shredded cheese, and half the crispy topping. I can assure you though, that if you’ll make the recipe as written you’ll be thrilled! This thing is really amazing.
• Use other vegetables: broccoli or green beans would also work with this recipe. I would par-boil them first.
• Other ingredients you could add: add sauteed onion to the sauce or top the casserole with crispy bacon crumbles.

How to make it step by step:

STEP 1: Cut the zucchini into thick slices – about 1/4-inch (7mm).

STEP 2: Brown the zucchini in a pan. This step is necessary – cooking the zucchini in oil adds so much flavor to this otherwise bland vegetable and also removes the excess water from it. Zucchini has really lots of water, so without removing it, the casserole would be too runny. Frying the zucchini doesn’t take up much time – I usually cook it simultaneously on two pans over high heat. The zucchini doesn’t have to be tender, just browned on both sides. The cooking time will depend on the pan type – non-stick pans take long to brown vegetables, also heavy-bottomed frying pans. The best would be here cast iron skillet or another frying pan with a thin bottom that browns the vegetables quickly. Another important thing is, don’t crowd the zucchini in the pan – you will be stewing it instead of frying, and getting these brown marks will take much longer. It’s also possible that such zucchini will be cooked through and too soft.

Alternatively you could roast the zucchini – toss it with olive oil and roast in an oven preheated to 445°F/230°C for about 10 minutes or put it under the broiler for a while. The other, more calorie-friendly method would be salting the zucchini, setting aside for about 30 minutes and patting dry with paper towels. Zucchini treated this way will lack some flavor, though.

STEP 3: Pat the zucchini with paper towels to remove excess fat then put in a large casserole dish.

STEP 4: Next, make the sauce. Remove the oil from the pan and add the butter. Cook finely chopped garlic in butter, then add the flour.

STEP 5: Add all the other ingredients for the sauce (milk, cream, mustard, lemon juice), and season with salt and pepper.

STEP 6: Cook the sauce just very briefly.

STEP 7: Make the breadcrumb topping: melt the butter, then stir in the breadcrumbs, then the Parmesan cheese.

STEP 8 (photos 7, 8, 9): Assemble the casserole: Toss the zucchini with the sauce, top with shredded Gruyere cheese, then with the breadcrumb and Parmesan topping.

STEP 9: Bake at 375°F / 190°C for about 30 minutes until golden brown and bubbly. Set aside for about 10 minutes allowing the casserole to set a little, then dig in!

Enjoy!

Storing instructions:

This zucchini gratin can be easily stored and reheated. It will still taste amazing. Store it in the fridge for up to 4 days (cover the baking dish). Reheat the whole casserole or just a couple of servings in an oven. I’m putting the casserole in a cold oven and set it to 375°F/190°C, then bake for about 15 minutes. I like to turn on the fan at the end of the baking to dry out the topping and make it more crunchy, just as freshly made. If you don’t have this option in your oven, you can put it under the broiler for a couple of minutes (keep an eye on it so it won’t burn). If your oven warms up more quickly than mine to may need to reduce the temperature a little.

I don’t recommend freezing this casserole. Theoretically, it would work but the zucchini would be very mushy and soft instead of a little crunchy. So it could be fine for a casual dinner but not for an important occasion.

What to serve it with:

This would be a perfect side dish to pair with roasted chicken, roasted turkey, or any of these recipes:

• Roasted duck with apples + how to roast a whole duck
• Turkey roulade with butternut squash, mushroom and cranberry stuffing
• Breaded chicken cutlets
• Chicken fritters 3 ways (cheesy, Italian and curried)
• Lemon Thyme Chicken Breast – baked in the oven
• Roasted turkey leg

You could also serve this very simply. When I’m making it on Sunday and have leftovers, I serve them for a quick weeknight dinner just with mashed potatoes and sunny side up eggs. It’s such a delicious dinner.

Did you make this recipe? RATE THE RECIPE or tell me in the COMMENTS how you liked it! You can also add a photo of your dish. It would make me very happy and will help other readers. Thank you!!