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Summer Vegetable Casserole: Healthy, Fresh & Light

The best seasonal ingredients of summer combine to make this delicious Summer Vegetable Casserole. This is the perfect dish to show off your garden bounty or the freshest ingredients from your local farmer’s market.

Ingredients for Summer Vegetable Casserole

1. Summer Vegetables

Of course, the main feature of this recipe is all the summer vegetables! Here are the vegetables you’ll use:

  • Zucchini
  • Yellow summer squash
  • Tomato
  • Sweet onion

Zucchini and yellow squash are summer staples, and gardeners never tire of finding ways to cook with them. This recipe features both seasoned with fresh herbs and spices. You could easily use either all zucchini or all yellow summer squash here, depending on what abounds in your garden.

chopped yellow squash and zucchini

Truly, my favorite thing about summer is the way that fresh vegetables taste. In particular, tomatoes of all types start exploding with flavor. Heirloom tomatoes are beautiful, open-pollinated, multi-colored varieties that have been passed down through family generations. If you have access to them, I recommend them in this recipe. You will be in for a real treat. Otherwise, any summer-fresh tomato variety will work well. Just look at the huge beefsteak tomato we found for ours. It was massive and mouth-watering!

large summer tomato

Pro tip: Regardless of the type of tomato you use, be sure to cut out the seeds and very juicy parts so your casserole doesn’t turn out watery.

2. Fresh Herbs and Spices

Another real treat in summer is being able to use fresh herbs from the garden. This recipe includes the following herbs and spices:

  • Fresh thyme
  • Fresh basil
  • Minced garlic
  • Garlic salt

If you don’t have fresh thyme or basil, you could substitute other fresh herbs you may have in your garden, such as rosemary or parsley. You could also substitute dried versions of your choice of herbs.

Pro tip: Using dried herbs instead of fresh herbs? Substitute 1 tsp of dried herbs for 1 Tbsp of fresh herbs.

3. Rice

You’ll use rice in this casserole dish. I used some jasmine rice that we had on hand, which worked well in the meal. However, whole grains are always a better option if you’re making a shopping decision for your health. Brown rice has more fiber, vitamins, and nutrients than white rice. (Source: Healthline)

4. Gruyère Cheese

Gruyère is a hard cheese from Switzerland. When it’s younger, Gruyère has a nutty flavor that is both distinct and decadent. You don’t have to use much of it to impart its flavor throughout the dish, which helps keep the overall fat and calorie content relatively low.

Grated Parmesan would make a good substitution for Gruyère in this recipe. You could also try gouda or mozzarella if you prefer a cheesier dish.

Making the Vegetable Casserole

This dish is simple to prepare. Here are the steps:

  • Preheat the oven to 350 degrees and lightly spray a 3-quart casserole dish with cooking spray.
  • Heat the oil in a skillet over medium heat until fragrant. Cook the minced garlic for about one minute.
  • Add the onion, zucchini, and yellow squash to the skillet. Season with garlic salt and thyme. Cook, stirring occasionally, for about 5 minutes, until the vegetables just start to get tender.
  • Add your mixture to a large bowl, then add tomato, basil, prepared rice, and 1 cup of grated Gruyère cheese. Spread everything evenly into your casserole dish and top with the remaining 1/2 cup of cheese.

summer vegetable casserole ingredients being stirred

  • Bake uncovered for 20 minutes.
  • Then enjoy! This serves 6.

More Recipes with Summer Vegetables

Do you still have more garden veggies to use up? Here are some more recipes for you to try:

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summer vegetable casserole
Print Recipe
5 from 1 vote

Summer Vegetable Casserole

Prep Time20 mins
Cook Time25 mins
Total Time45 mins
Servings: 6


  • 1 Tbsp olive oil
  • 2 cloves garlic minced
  • 1/2 sweet onion chopped
  • 1 zucchini coarsely chopped
  • 1 yellow squash coarsely chopped
  • 1/2 tsp garlic salt
  • 2 Tbsp fresh thyme chopped, or 2 tsp dried thyme
  • 2 Tbsp fresh basil chopped
  • 1 large heirloom tomato seeded and coarsely chopped
  • 1 cup prepared rice such as jasmine or brown
  • 1.5 cups Gruyère cheese grated, divided


  • Preheat oven to 350 degrees. Lightly spray a 3-quart casserole dish with cooking spray.
  • Heat the oil in a skillet over medium heat until fragrant. Cook the garlic for about one minute.
  • Add the onion, zucchini, and yellow squash, and season with garlic salt and thyme. Cook, stirring occasionally, for about 5 minutes.
  • Combine mixture in a large bowl with tomato, basil, prepared rice, and 1 cup of Gruyère cheese. Spread evenly into casserole dish and top with remaining cheese.
  • Bake uncovered for 20 minutes.
  • Enjoy!


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