Roasted Vegetable Gratin

Roasted Vegetable Gratin

This super flavorful, nutrient-dense casserole is a simple recipe to prepare that will absolutely satisfy your comfort food cravings. Roasting the colorful vegetables enhances the flavor, while adding the cheeses, and covering with a fresh tomato sauce will surely make this a family favorite!

Preparation time: 20 minutes

Cooking Time: 60 minutes

Yield: 6 Main Dish Servings


  • 4 pounds zucchini and summer squash and/or eggplant sliced into 1/4 inch pieces
  • 8 cups tomatoes, coarsely chopped
  • 1/2 cup yellow onion, finely chopped
  • 1 tablespoon garlic, minced
  • 2-3 red, green or yellow peppers cored and sliced into 1-1/2” thick strips
  • 1/3 cup fresh basil, coarsely chopped
  • 3 tablespoons oregano, coarsely chopped
  • 1 cup mozzarella cheese, shredded (organic, if available)
  • 1/2 cup parmesan cheese, grated (organic, if available)
  • 1-2 teaspoons of balsamic vinegar
  • 1 teaspoon, salt
  • 1/4 cup olive oil (divided)

Optional Add-ins:

  • 1 pound of mushrooms, chopped
  • 2 cups of greens, sautéed and chopped
  • 8 ounces of tempeh, (plant based protein) broken into small pieces


Preheat oven to 425.  Lightly oil two large sheet pans and set aside.

Arrange the zucchini, squash and eggplant in a single layer on the sheet pans.  Roast about 10-12 minutes, set aside when done.

In a large saucepan, warm 2 tablespoons of the olive oil and gently add the onion, stir and cook until the onion is translucent, approximately 5-6 minutes.  If using any of the optional ingredients, you may add at this point and cook for an additional 4-6 minutes.  Add the garlic, tomatoes and oregano and reduce the heat to medium or low.  Simmer, stirring occasionally until the sauce has thickened nicely, approximately 20 minutes.

Remove from heat and stir in the basil, vinegar and salt.  If sauce remains chunky you may use a small immersion blender to smooth.

Lightly oil the bottom and sides of a baking dish.  Spread a thin layer of sauce on the bottom, then arrange approximately 1/3 of the vegetable slices on top, overlapping slightly.  Follow with another layer of the sauce, sprinkle with the cheeses.

Repeat the above process two more times, topping with parmesan cheese.

Bake, uncovered at 325’ for approximately 20 minutes until the sauce bubbles and the top is golden.  Check after 10 minutes.  If browning too quickly you may cover loosely with aluminum foil.

When baking is complete, cool for a minimum of 15 minutes to set before serving.