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Summer Vegetable Casserole

Light and Healthy Vegetable Casserole
Casey Barber
Cook Time:
45 mins
Prep Time:
15 mins

Chef notes

When you think of the best time to bake and serve a casserole, summer probably isn’t the first season that comes to mind. Casserole are often rich, cheesy and therefore heavy, which means they’re typically better-suited for the cooler months when we crave extra comforting food. This casserole, however, is an anomaly. It’s not the least bit heavy and just creamy enough. Tomatoes, zucchini, yellow summer squash, corn and green beans lend loads of color and ensure that it’s both vibrant and interesting. This is a summer dish that absolutely captures seasonal produce.

With five different layers of vegetables in this casserole, you might worry that it’ll be far too complicated to make. That couldn’t be further from the truth. If you happen to own a mandoline, this is a perfect time to use it. The Japanese slicer makes quick work out of slicing the vegetables and also ensures that they’re sliced more thinly and evenly than you could achieve with just a knife. You can assemble the casserole a few hours before you plan to bake it and store it in the refrigerator. Let it sit out at room temperature while the oven preheats, then bake according to directions.

Tucked in between the vegetable layers is a leek- and shallot-studded yogurt sauce. This addition not only helps bind each layer but it provides added flavor and creamy richness. The cheesy panko breadcrumb topping provides crunch and added satisfaction so it’s a casserole that can easily hold its own. Enjoy this summer vegetable casserole as a side with your favorite grilled meats and fish, of course, but know that it makes a wonderful vegetarian main dish, too. 

Get Ingredients: If you don’t have everything you need on hand, you can easily purchase all of the ingredients (just click the orange button below that says ‘Get Ingredients’). You can pick and choose exactly what ingredients you need based on what’s in your pantry and they’ll be on your doorstep before you know it. 



  • 1 tablespoon extra-virgin olive oil
  • 1 large leek (white and light green parts only), cleaned and sliced into half-moons
  • 1 large shallot, minced
  • 1/2 teaspoon kosher salt
  • 1/2 cup Greek yogurt
  • 1/4 cup chicken or vegetable broth
  • 1 medium zucchini, thinly sliced into rounds
  • 1 medium yellow squash, thinly sliced into rounds
  • 2 large tomatoes, thinly sliced into rounds
  • 2 large ears of corn, kernels only
  • 1/2 pound green beans, trimmed and cut into bite-size pieces
  • 1/3 cup panko breadcrumbs
  • 1 tablespoon finely grated Parmesan or pecorino cheese
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Preheat the oven to 375 degrees F.


Heat the olive oil in a large skillet over medium heat. Stir in the leek, shallot and salt. Cook, stirring occasionally, for about 5 minutes until the leek is starting to soften, then cover and continue to cook for about 5 minutes more until the leek is very soft. Remove from the heat and transfer to a bowl. Stir in the yogurt and broth.


Assemble the casserole: Line a 9-inch round or square casserole dish with a layer of zucchini and yellow squash, alternating rounds if desired for a colorful presentation. Top with a layer of tomato slices, then half the corn and half the green beans.


Spoon half the leek and yogurt mixture evenly over the vegetables, then repeat with the remaining vegetables and leek/yogurt mixture for a second layer. The top layer may rise slightly higher than the top of the casserole dish; it will sink slightly as the vegetables cook.


In a small bowl, combine the panko and Parmesan, then sprinkle evenly over the top of the casserole.


Cover the casserole loosely with foil and cook for 30 minutes, then remove the foil and cook for 15 to 20 minutes more to toast the panko topping.