Summer Vegetable Gratin

Professional Chef Chris Styler shares the perfect side dish for when your garden is overrun with zucchini and other yummy veggies. Start cooking!

If your garden—or the farmers’ market—is overrun with zucchini, yellow squash, eggplant, and tomatoes, this summer vegetable gratin is just the side dish you’re looking for! It may look like a long, involved recipe, but the parts that go on to make the whole are very easy to put together, and the rewards are delicious!

Summer Vegetable Gratin

Ratatouille - French cuisine

Summer Vegetable Gratin

Course Main Course
Cuisine French
Servings 6 Serves


  • 1 tablespoon olive oil
  • 1 medium onion, finely diced
  • 2 teaspoon minced garlic

Tomato-Herb Broth

  • 1/2 cup water
  • 1 tablespoon tomato paste
  • ¼ cup assorted herb sprigs, coarsely chopped


  • 1/3 cup shredded Parmesan cheese
  • 1/3 cup shredded mozzarella or Gruyere cheese
  • 1/3 cup panko or other coarse bread crumbs


  • 1 tablespoon olive oil, plus a little more for greasing the baking dish
  • 1 medium zucchini (about 8 ounces)
  • 2 medium yellow squash (about 8 ounces)
  • 2 small Japanese eggplants (about 12 ounces), sliced; or 1 large regular eggplant, with slices halved
  • 1 large ripe tomato
  • 1 teaspoon kosher salt
  • ½ teaspoon black pepper Fresh chopped parsley and/or chopped basil


  • Preheat the oven to 400° F.
  • Heat 1 tablespoon of the olive oil in a medium skillet over medium heat. Add the onion and garlic and cook, stirring, until the onion is tender and lightly browned, about 8 minutes.
  • Stir the water and tomato paste together in a small saucepan and add the herbs. Bring to a boil. Cover the pan and lower the heat to low, simmer for 10 minutes.
  • While the onion and broth are going, wash the vegetables and cut them on a slight diagonal into ½-inch or so rounds.
  • Using your fingertips, rub the panko, Gruyere, Parmesan and the remaining tablespoon of oil together in a small bowl until the oil is absorbed.
  • Grease an 8 x 8-inch square baking dish with olive oil. Spread the softened onion and garlic in the bottom of the dish. Make a row of eggplant slices, slightly overlapping them.
  • Repeat with zucchini, yellow squash, and tomatoes. Keep making alternating rows of vegetables until the dish is full. The vegetables should be fairly snug but not crammed into the dish. Strain the herb broth over the vegetables. Season the vegetables with salt and pepper. Cover the dish with aluminum foil and bake until the vegetables are tender, about 40 minutes.
  • Remove the foil, crumble the topping over the vegetables and bake, uncovered, until the topping is golden brown and the vegetables are very tender, about 20 minutes. Let sit at least 10 minutes before cutting and serving (good at room temperature, too). To make nice, neat slices of the gratin, make sure to cut the layers of vegetables all the way down to the bottom and sides of the dish before trying to lift them out.
Keyword potato and vegetable gratin, vegetarian potato bake

Serves 6, as a side dish.

Print Friendly, PDF & Email
Vegetable - Summer vegetable gratin
Chris Styler

Christopher Styler is an experienced chef, teacher, culinary producer, and author, with over 35 years of experience in the food world. A graduate from the Culinary Division of Johnson & Wales University, he is currently working on a cookbook as well as keeping active in television production. His website, Freelance Food LLC, is at

Notify of
Recipe Rating

Oldest Most Voted
Inline Feedbacks
View all comments
Roland Stirk

My husband and I have been trying to start our first vegetable and herb and some Fruit garden this year. Therefore, we planted numerous seeds in small pots and kept out of the frost until after our last frost date for our area – however, it has now been approximately 1 month and we still have very few things that have started to sprout.


Thanks, Jenni! Gonna bake up some little 2-serving casseroles for the freezer. Once they are frozen, then suck the air out and, Voila! – sides for the winter!


I would cook it half way before freezing. Fresh frozen tomatoes have a funky taste and wouldnt thaw before cooking just make sure its hot all the way through


Can this casserole be frozen? Would I do it before or after baking? A great way to have the garden bounty all winter, if it works!


Typo! I mean, I want to use them up.


Glad you posted this because I have an abundance of yellow squash/tomato and I don’t want to use them up. Going to try this today. Thanks 🙂

Plan Your Day. Grow Your Life.

Get money-saving tips, weather updates and more! Sign up today.