Summer Tomato Zucchini Casserole

By Sally Cameron on August 08, 2016

Dairy Free, Gluten-Free, Paleo, Vegetables & Side Dishes, Vegetarian

Layers of red ripe tomatoes and green zucchini baked with a crisp, cheesy tasting herb topping; the best of summer vegetables all in one dish. Tomato zucchini casserole is a great summer side dish for your family, so bake one tonight. And it’s dairy-free and gluten-free.

tomato zucchini casserole |

Summer Tomato Zucchini Casserole

Summer markets are overflowing with beautiful tomatoes, zucchini, and fresh herbs. Ever turn them into a casserole? Its sort of a traditional summer French dish, a vegetable gratin, which is a fancy name for a casserole. Many casseroles use cheese for richness and breadcrumbs for a crisp topping. My version is lighter and cleaner without cheese or breadcrumbs, yet still a crisp top and a cheesy taste. How? Using the dairy-free cheesy sprinkle recipe I posted recently.

Dairy-Free Cheesy Sprinkle

Dairy-free cheesy sprinkle is made with raw cashews, nutritional yeast, granulated garlic and sea salt. If you are not familiar with the wonderful cheesy flavor of nutritional yeast, read this post for more information. You can make a batch in a minute in a food processor. It provides a cheesy taste with no cheese, so great for dairy-sensitive or paleo diners.

tomato zucchini casserole |

Ingredient Notes

For the casserole I use Roma tomatoes and green zucchini. Yellow zucchini is nice for added color if you can find it. Choose tomatoes and zucchini that are about the same diameter. When you slice and layer them the casserole looks nice and layers more easily. If they aren’t quite even, it still works. You will need lots of fresh thyme, olive oil, garlic and a large shallot. If you don’t have any shallot you could use a little thinly sliced onion.

tomato zucchini casserole |

How to Assemble the Casserole

Use an oval casserole dish called a gratin, oval roaster, or oval casserole. Use a 4 quart size. My dish is approximately 13″ long, 10″ wide and 2 1/2 ” deep. You can also use a rectangular casserole. Just arrange the vegetables in rows rather than an oval.

Slice the tomatoes and zucchini crosswise into about 1/4″ thick circles. Sauté shallot and garlic in olive oil until soft and place it in the bottom of the casserole, then top with overlapping layers of tomatoes and zucchini. Pack the slices fairly tight as they will shrink during baking. Sprinkle the topping over the top and bake uncovered until golden, about 35-45 minutes. Serve to the happy smiles of your family.

tomato zucchini casserole |

Another idea for summer tomatoes is tomato gazpacho soup. It’s cool, refreshing and delicious!

tomato zucchini casserole |
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Tomato Zucchini Casserole

Layers of sliced tomatoes and zucchini baked into a casserole with a dairy-free, gluten-free cheesy tasting herb topping.
Servings 4 -6 servings


  • 6 Roma tomatoes about 1 1/4 pounds
  • 3 zucchini about 3/4 - 1 pound
  • 2 shallots 3/4 cup sliced shallot
  • 3 large garlic cloves finely chopped
  • 3 tablespoons dairy free cheesy sprinkle click recipe link
  • 1 1/2 tablespoons fresh chopped thyme leaves half a bunch
  • 1/8 teaspoon sea salt
  • 1/8 teaspoon ground black pepper
  • 2 tablespoons extra virgin olive oil divided use


  • Pre-heat an oven to 375° degrees. Slice tomatoes and zucchini crosswise into approximately 1/4" slices.
  • Add 1 tablespoon of olive oil to a small pan and heat oil over medium low heat. Add the shallot and cook until soft, about 2-3 minutes. Add garlic and cook another 30-60 seconds. Spread the soft shallots and garlic into the bottom of a 4 quart oval casserole.
  • Layer the tomato and zucchini slices alternately around the dish, starting at the outside and working in, overlapping tightly. Get as much as you can into the dish. You may not use quite all of the slices. Sprinkle with the salt and pepper.
  • Combine the dairy-free cheesy sprinkle with the chopped thyme leaves then sprinkle over the top of the casserole. Drizzle with the last tablespoon of the olive oil.
  • Bake casserole until top is golden and crisp, about 35-45 minutes. Timing will depend on your ovens. Serve warm.
  1. Denise - August 9th, 2016

    Perfect! It looks delicious! I am testing different yeast powder for a best taste. I bought one that I didn’t like at all. It smells bad! What brand are you using?

  2. Sally Cameron - August 10th, 2016

    Hi Denise. I bought it on Amazon, Sari Foods. Non-GMO, no synthetic vitamins, organic, really good. Think I put the link in the post. I will check the post right now for the cheesy sprinkle…

  3. Debbie in Alaska - May 17th, 2018

    Do you think you could do this in a crockpot???

  4. Sally Cameron - May 23rd, 2018

    Hi Debbie. I don’t think a crock pot would work. This is an oven kind of recipe.

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