Summer Vegetable Gratin

So I don't have any farmers' market finds for you this morning because I'm working today and can't make my usual trip to the farmers' market... but I can show you what I made with last week's finds!

When I came home toting a globe zucchini, cousa squash, and summer squash last Saturday, I already kind of knew which recipe I would be turning to. Within the pages of Thomas Keller's Ad Hoc at Home is a two-page spread featuring pictures of the components of his summer vegetable gratin. I knew the recipe would be a great way to showcase my farmers' market finds.

I made a trip to Whole Foods to pick up ingredients I hadn't gotten at the farmers' market like an eggplant, some plum tomatoes, an onion, and thyme.

And then I became a sauteeing and slicing machine, making my way through the steps in the recipe. I changed the steps around from the original recipe because I think it makes sense to start sauteeing the onion first and then slice the veggies during the 20 minutes the onion needs to be cooking.

Also, while Keller's version is made in a round or oval gratin dish, I opted to use two miniature gratin dishes and a small square dish. And while his vegetable circles were all relatively the same size, mine ranged wildly from the chubby globe zucchini to the svelte summer squash. For this reason, if I make the gratin with different size vegetables again, I think I will alternate the kinds of vegetables within rows instead of forming one row for each vegetable. It's easy enough to take bites of all of them once they're on your plate though, so either way works.

Summer vegetable gratin

Summer Vegetable Gratin (adapted from Ad Hoc at Home)


Canola oil
1 medium onion, coarsely chopped
2 garlic cloves, minced
1 tablespoon plus 1 teaspoon chopped thyme
2 or 3 plum tomatoes
2 small summer (yellow) squash
1 small globe zucchini
1 small cousa squash
1 small eggplant
1/4 cup extra virgin olive oil, plus more for drizzling
Kosher salt
1/2 cup freshly grated Parmigiano-Reggiano
1/2 cup bread crumbs


Preheat oven to 350 degrees. The original recipe says to set a rack in a baking sheet, but then it never says what to do with that setup. I ended up placing my baking dishes on it, thinking it might be good to have in case they bubbled over (which they didn't).

Heat some canola oil in a large frying pan over medium heat. Reduce heat to medium-low, and add onions and garlic. Cook, stirring occasionally, until onions are translucent, about 20 minutes. Stir in 1 tablespoon of thyme.

Slice all of the vegetables in 1/4-inch thick slices. (Discard ends.)

Combine summer squash, zucchini, cousa, and eggplant in a large bowl. Toss with olive oil, and season with salt.

Drizzle tomato slices with olive oil, and season with salt.

Combine Parmesan, bread crumbs, and remaining thyme in a small bowl.

Divide onion mixture among baking pans, and spread it to cover the bottoms of the pans.

Then begin layering the vegetables. In the biggest pan, make a row of overlapping zucchini slices, and sprinkle with bread crumb mixture.

Next make a row of overlapping summer squash slices, making sure they slightly overlap the zucchini slices. Sprinkle with bread crumb mixture.

Make a row of overlapping tomato slices, making sure they slightly overlap the squash slices. Sprinkle with bread crumbs.

Repeat with eggplant slices and cousa slices.

Sprinkle top with more of bread crumb mixture and a little salt.

Use any extra veggies and bread crumb mixture to make mini casseroles in mini gratin dishes.

Place all baking dishes on rack set in baking pan and bake for about 1 1/2 hours, or until veggies are tender.

Summer vegetable gratin

Let cool slightly before serving. (The original recipe says to remove the gratin from the oven, let it rest for 10 minutes, and then pop it under the broiler, but I thought the tops of mine browned nicely enough and didn't need any broiling, so I just took them out once the veggies were ready.)

The gratin is delicious on its own since it's chock-full of veggies and just screams summer, but if you want to make it a little more filling, I recommend serving it with some orzo drizzled with olive oil and sprinkled with salt, pepper, and thyme.

Summer vegetable gratin

The gratin reheats well and is actually more flavorful the next day. Feel free to change it up using your own farmers' market finds.
What have you made with your farmers' market finds this week? 

Need another idea? Try this roasted beet salad with walnut vinaigrette.