Few dishes celebrate the vibrant flavors of the season like a Summer Gratin. Imagine layers of colorful zucchini, yellow squash, juicy tomatoes, and sweet red onions, all baked with a savory topping of golden, cheesy panko. This comforting, sun-kissed side bursts with Mediterranean essence, making it a staple at any summer table. Whether you’re entertaining friends or just treating yourself to a fresh veggie bake, Summer Gratin is the kind of recipe that transforms simple ingredients into a stunning, flavor-packed dish everyone loves.

Ingredients You’ll Need

You only need a handful of fresh, easy-to-find ingredients to make this Summer Gratin shine. Each one brings something special, creating a beautiful combination of taste, color, and texture that’s so much more than the sum of its parts.

Zucchini: Thinly sliced for quick, tender cooking and a touch of mild, earthy flavor.
Yellow squash: Brings sunshine yellow color and a slightly sweeter note than zucchini.
Tomatoes: Juicy slices add tangy brightness and rich umami to each bite.
Red onion: Offers subtle sweetness and a pop of purple for visual appeal.
Garlic: Minced garlic infuses deep flavor throughout the bake.
Olive oil: Helps the veggies caramelize and ties all the flavors together.
Salt: Essential to bring out the natural flavors of the veggies.
Black pepper: Just enough for a gentle kick and depth.
Dried thyme: Adds aromatic, herby notes that scream summer garden.
Parmesan cheese: Grated for a nutty, irresistibly savory crust.
Panko breadcrumbs: Give the topping that perfect golden crunch.
Melted butter: Mixes with panko for rich, buttery flavor in every crumb.
Fresh basil: The final flourish, providing fresh aroma and a bright, herbal finish.

How to Make Summer Gratin

Step 1: Prep the Oven and Baking Dish

Start by preheating your oven to 375°F, getting it nice and hot for an even bake. Lightly grease your favorite baking dish—whether it’s a round pie plate or a classic casserole—to ensure that beautiful Summer Gratin will lift out effortlessly when it’s time to serve.

Step 2: Slice and Toss the Vegetables

Grab all the fresh produce: zucchini, yellow squash, tomatoes, and onion. Slice them thinly for faster cooking and a lovely layered effect. In a large mixing bowl, toss the veggies with minced garlic, olive oil, salt, black pepper, and dried thyme until every piece glistens and is well coated in herby goodness.

Step 3: Layer the Vegetables for the Perfect Gratin

Arrange the vegetables in your prepared dish by slightly overlapping the slices in a shingled, circular or row pattern. This not only looks stunning but ensures even cooking and mingling of flavors. Try alternating colors—it’s visually impressive and a joy to serve!

Step 4: Cover and Bake

Cover the dish with foil and place it in the oven. Bake for 25 minutes so the veggies soften, release their juices, and start to meld together. This gentle steam is what gives Summer Gratin its luscious, tender texture.

Step 5: Add the Crunchy Topping and Finish Baking

While the veggies bake, melt butter and stir together with panko breadcrumbs and grated Parmesan cheese. Remove the foil from the dish, sprinkle the topping evenly over the vegetables, and return it to the oven. Bake uncovered for another 15 to 20 minutes, until the topping turns golden and the gratin is bubbling around the edges. The kitchen will smell divine!

Step 6: Garnish and Serve

Just before serving, shower your Summer Gratin with fresh, torn basil leaves. The basil’s peppery aroma brightens every bite and makes the whole dish pop with color and flavor.

How to Serve Summer Gratin

Garnishes

Nothing says fresh quite like a handful of torn or chiffonade basil scattered atop your Summer Gratin. If you want to go the extra mile, sprinkle a little extra Parmesan or a drizzle of really good olive oil over each serving. These finishing touches take both flavor and presentation up a notch!

Side Dishes

Summer Gratin is a superstar alongside grilled meats like chicken or fish, or paired with your favorite plant-based proteins for a satisfying vegetarian meal. It’s lovely next to a crisp green salad with vinaigrette, crusty bread for dipping, or even a scoop of chilled quinoa for a little extra heft.

Creative Ways to Present

Embrace the beauty of this Summer Gratin by assembling it in individual ramekins for elegantly portioned servings at dinner parties. Or layer the veggies in a tart pan for a stunning centerpiece presentation. For a rustic feel, serve it straight from a cast-iron skillet, letting everyone help themselves family-style.

Make Ahead and Storage

Storing Leftovers

If you’re lucky enough to have leftovers, let the Summer Gratin cool completely before covering and refrigerating. Stored in an airtight container, it will stay fresh and flavorful for up to three days, making it a smart option for meal prep or speedy lunches.

Freezing

While you can freeze Summer Gratin, be aware that the water content in the vegetables will change the texture ever so slightly when thawed. For best results, freeze portions wrapped tightly and reheat directly from frozen. The topping will lose some crispness, but the taste remains delightful.

Reheating

To reheat, place leftover Summer Gratin in a 350°F oven and bake, uncovered, until warmed through and the topping is re-crisped, about 15 minutes. You can also use a microwave, but the oven will bring back that delicious, crunchy topping.

FAQs

Can I use different vegetables in Summer Gratin?

Absolutely! While zucchini, squash, and tomatoes are classic, you can swap in eggplant, potatoes, or bell peppers depending on what’s in season or your personal favorites. Just slice everything thinly for even baking.

How do I keep the gratin from getting watery?

Make sure to slice your vegetables thin and let excess liquid evaporate by baking uncovered after adding the topping. Salting the vegetables lightly and letting them sit for a few minutes before assembling can also help draw out moisture.

Can I make Summer Gratin vegan?

Yes! To keep it vegan, substitute the Parmesan for a dairy-free alternative, use vegan butter in the topping, and double-check your panko is egg-free. The results will still be deliciously crispy and flavorful.

What’s the best way to slice the vegetables for this recipe?

A mandoline slicer makes quick work of getting those perfectly even, thin slices, but a sharp knife works fine too. Consistent thickness helps everything cook at the same rate for a perfect Summer Gratin every time.

How far in advance can I assemble Summer Gratin?

You can layer the veggies and cover the dish up to one day ahead, keeping it refrigerated. Wait to add the topping until just before baking so it stays nice and crunchy.

Final Thoughts

This Summer Gratin is truly a celebration of fresh vegetables and bold flavors, and it’s the kind of dish that brings people together over a shared love of good food. Whether you enjoy it as a vibrant side or a light vegetarian main, you owe it to yourself to give it a try—summer on a plate has never tasted so satisfying!

Summer Gratin Recipe