Mushroom, Leek, and Zucchini Gratin

With a Parmesan and sourdough bread crumb topping, meaty mushrooms, and juicy Roma tomatoes, this zucchini gratin is a perfect side dish to any meal.

• Preparation Time: 10 mins
• Cooking Time: 1 hr 20 mins
• Total Time: 1 hr 30 mins
• Calories: 180 Calories

Ingredients

• ½ teaspoon salt
• ½ cup grated Parmesan cheese
• ¼ teaspoon ground black pepper
• ½ cup chopped fresh parsley
• 1 tablespoon chopped fresh tarragon
• 2 medium yellow squash
• 1 medium yellow onion, chopped
• 4 tablespoons extra-virgin olive oil, divided
• 2 cups chopped leeks
• 2 cups sliced white mushrooms
• 2 medium zucchini
• 1 pound Roma tomatoes
• 1 cup sourdough bread crumbs
• ¼ cup finely chopped cashews

Recipe Instructions

Step 1

Preheat the oven to 375 degrees F (190 degrees C). Lightly grease a 3-quart casserole dish.

Step 2

Heat 2 tablespoons oil in a large, nonstick skillet over medium heat. Add leeks and onion to the hot skillet and saute for 10 minutes. Add mushrooms and continue to saute until leeks and onion are tender, 6 to 8 more minutes.

Step 3

Meanwhile, cut zucchini, yellow squash, and Roma tomatoes into 1/4-inch slices.

Step 4

Transfer mushroom mixture to the prepared casserole dish and spread evenly over the bottom. Layer zucchini, yellow squash, and tomatoes on top of the onion mixture.

Step 5

Combine bread crumbs, Parmesan cheese, parsley, cashews, tarragon, salt, and pepper in a large mixing bowl. Sprinkle over the vegetables to cover.

Step 6

Bake in the preheated oven until gratin is dark brown all over, about 1 hour.