Summer Vegetable Gratin with Fresh Zucchini and Tomatoes

Summer Vegetable Gratin

Every summer I make the same mistake at the farmers market. I promise myself I will buy one zucchini, one yellow squash, and a couple of tomatoes, and then I walk home with a tote bag so heavy the handles creak.

If your counter is buried under summer produce right now, this summer vegetable gratin is exactly what you need. Holy buckets, is it good.

This is one of those baked side dishes that looks like you fussed, but the whole thing is really just slicing and layering.

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Zucchini, yellow squash, and tomatoes get stacked over a bed of shallots cooked down with garlic and fresh herbs, then the pan bakes under foil until everything turns tender. After that comes the part I dream about.

Three quarters of a cup of freshly grated parmesan goes over the top, and the whole dish goes back into the oven until that cheese is golden and bubbly.

Let me walk you through the shape of it, because once you see how simple the pieces are, you will be making this on repeat all season.

You start by softening 4 chopped shallots (or 2 small sweet onions if that is what is in your pantry) in 2 Tablespoons of extra virgin olive oil over medium heat. Give them 5 to 7 minutes with a good pinch of salt and pepper.

Then in goes 4 minced garlic cloves for one more minute, followed by 1/4 cup of chopped fresh basil and 2 teaspoons of chopped fresh thyme.

That herby, garlicky mixture gets spread across the bottom of the baking dish, where it becomes the flavor floor for everything stacked on top.

Next comes the vegetable tower. Slice 2 medium yellow squash and 1 medium zucchini into 1/4 inch rounds, toss them in a large bowl with a light drizzle of extra virgin olive oil, salt, and pepper, then arrange them in the dish in slightly slanted rows.

The tomatoes follow the same pattern, sliced 3/4 inch thick. I reach for 6 Roma tomatoes most of the time because they hold their shape so beautifully, but 4 vine ripened tomatoes work just as well. Pick whichever looks best at your market that day. That is the only rule.

Here is the trick that keeps this gratin from turning into a watery casserole. Cover the dish with foil and bake it for 30 to 35 minutes first.

The foil traps steam, so the vegetables cook through and turn tender when you pierce them with a knife without collapsing into mush.

Then the foil comes off, the parmesan goes on, and the pan returns to the oven uncovered for another 10 to 15 minutes. That is when the cheese melts, browns, and bubbles around the edges of every single slice.

Do not skip the 10 minute rest at the end. It lets the layers settle so the slices hold together when you serve them.

About the pan. I use a 7×11 inch baking dish, sprayed with nonstick spray before anything goes in. An 8×8 inch dish also works if that is what you have, though the layers will sit a little deeper.

Either way, set the oven to 375 degrees Fahrenheit before you start slicing, because the shallots cook quickly and you want that heat waiting for you.

What I love most is how forgiving this recipe is with whatever produce you already own. Extra zucchini? Add it. Slightly more basil because the plant is going wild? Go for it. The structure stays the same: herby base, sliced vegetables in rows, foil, parmesan, golden finish.

• The base: shallots, garlic, basil, and thyme softened in olive oil
• The middle: zucchini and yellow squash, sliced 1/4 inch thick and lightly oiled
• The top: tomatoes sliced 3/4 inch thick, layered in slanted rows
• The finish: 3/4 cup freshly grated parmesan, baked until golden and bubbly

One more thing about the tomatoes. Some weeks the Roma tomatoes at my store look tired and pale, so I grab vine ripened ones instead. The recipe is built for either, and honestly, choosing the better looking tomato matters more than choosing the correct one.

This dish is gorgeous enough for company and easy enough for a Tuesday. I have brought it to cookouts, set it next to grilled chicken on a weeknight, and eaten leftovers straight from the fridge standing at the counter.

It also happens to be a genuinely light side, and it is naturally gluten free, which makes it an easy yes when I am feeding a crowd with mixed dietary needs.

If you are wondering what to serve with it, I usually keep things simple. Grilled chicken, a piece of salmon, or a big pile of burgers off the grill all work beautifully, because the gratin brings so much brightness to the plate.

On a hot night, I have made a meal of it with nothing but a slice of crusty bread and a glass of something cold.

As for timing, the whole thing takes about an hour, with 15 minutes of prep and 45 minutes of oven time, and it serves 6 as a side. That said, I have watched four people demolish the entire pan, so plan accordingly.

If you are feeding a bigger group, use the 8×8 inch dish and trust the knife test to tell you when the vegetables are ready.

Leftovers are honestly a joy. I have eaten this cold the next day straight from the container, and I have also warmed a portion in the oven until the parmesan went crisp again. Either way, it disappears fast.

Ingredients

Here is everything you need for one 7×11 inch gratin. Nothing fancy, just a short list of summer vegetables and a few pantry staples.

• 2 Tablespoons extra virgin olive oil, plus more for drizzling
• 4 shallots or 2 small sweet onions, chopped
• Salt and pepper, to taste
• 4 cloves garlic, minced
• 1/4 cup chopped fresh basil
• 2 teaspoons chopped fresh thyme
• 6 Roma tomatoes or 4 vine ripened tomatoes, sliced 3/4 inch thick
• 2 medium yellow squash, cut into 1/4 inch slices
• 1 medium zucchini, cut into 1/4 inch slices
• 3/4 cup freshly grated parmesan cheese

A quick note on the parmesan. Grate it yourself if you possibly can. The bagged shredded stuff does not melt the same way, and that bubbly golden crust is the whole point of this dish.

Directions

This is a straightforward assembly, so read through it once and then dive in. The oven does the heavy lifting.

1. Preheat and prep the dish. Preheat the oven to 375 degrees Fahrenheit. Spray a 7×11 inch baking dish with nonstick spray and set it aside.
2. Soften the shallots. Heat 2 Tablespoons of extra virgin olive oil in a large skillet over medium heat. Add the chopped shallots or onions, season with salt and pepper, and saute until softened, 5 to 7 minutes.
3. Add the garlic and herbs. Stir in the 4 minced garlic cloves and cook for 1 more minute, just until fragrant. Add 1/4 cup chopped fresh basil and 2 teaspoons chopped fresh thyme, stir to combine, then transfer the mixture to the prepared baking dish and spread it into an even layer across the bottom.
4. Layer the vegetables. Add the sliced zucchini and yellow squash to a large bowl, drizzle lightly with extra virgin olive oil, and season with salt and pepper. Layer the vegetables in slightly slanted rows until you run out of room or use up all the slices, tucking the tomato slices in among them. Season the top with salt and pepper.
5. Bake covered. Cover the baking dish with foil and bake for 30 to 35 minutes, until the vegetables are tender when pierced with a knife but not mushy.
6. Add the parmesan and finish. Remove the foil and sprinkle 3/4 cup freshly grated parmesan cheese over the top. Return the dish to the oven uncovered and bake until the cheese is golden brown, 10 to 15 minutes.
7. Rest and serve. Let the dish sit for 10 minutes before slicing and serving, so the layers hold together on the plate.

A couple of small things that make a big difference. Slice the squash and zucchini evenly, because uneven rounds cook at different speeds and you will end up with some mushy pieces sitting next to firm ones. And trust the knife test over the clock.

If your knife slides through a slice of squash with no resistance, you are ready for the cheese.

Recipe details

Prep time is 15 minutes, cook time is 45 minutes, total time is about 1 hour, and the recipe serves 6.

Per serving, the source nutrition comes in around 135 calories, 10 grams of carbohydrates, 6 grams of protein, and 9 grams of fat.

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Summer Vegetable Gratin Every summer I make the same mistake at the farmers market. I promise myself I will buy one zucchini, one yellow squash, and a couple of tomatoes, and then I walk home with a tote bag so heavy the handles creak.

• Total Time: 60 min
• Yield: 6 1x

Ingredients

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Ingredients
2 Tablespoons extra virgin olive oil
4 shallots, chopped
salt and pepper
4 cloves garlic
1/4 cup fresh basil, chopped
2 teaspoons fresh thyme, chopped
6 Roma tomatoes, sliced 3/4” thick
2 medium yellow squash, cut into 1/4 inch slices
1 medium zucchini, cut into 1/4 inch slices
3/4 cup parmesan cheese, freshly grated

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Instructions

Directions
1-Preheat oven to 375 degrees: Preheat oven to 375 degrees. Spray a 7×11″ baking dish with nonstick spray then set aside.
2-Heat 2 Tablespoons extra virgin olive oil: Heat 2 Tablespoons extra virgin olive oil in a large skillet over medium heat. Add shallot or onions, season with salt and pepper, and then saute until softened, 5-7 minutes. Add garlic then saute for 1 more minute. Add fresh basil and thyme then stir to combine. Transfer mixture to prepared baking dish then spread into an even layer in the bottom.
3-Add sliced zucchini and yellow squash to: Add sliced zucchini and yellow squash to a large bowl then drizzle lightly with extra virgin olive oil and season with salt and pepper. Layer the vegetables in slightly slanted rows until you run out of room or all the vegetables are used up. Season the top with salt and pepper then cover the baking dish with foil and bake for 30-35 minutes, or until the vegetables are tender when pierced with a knife. Remove foil then sprinkle parmesan cheese on top. Return to oven uncovered then bake until cheese is golden brown, 10-15 minutes. Let dish sit for 10 minutes before serving.

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• Prep Time: 15 min
• Cook Time: 45 min
• Method: bake

Nutrition

• Calories: 135kcal
• Sugar: 5g
• Sodium: 228mg
• Fat: 9g
• Saturated Fat: 3g
• Carbohydrates: 10g
• Fiber: 2g
• Protein: 6g
• Cholesterol: 11mg