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Heirloom Tomato Gratin

Heirloom Tomato Gratin

Heirloom tomatoes are sweet, plump and full of the best flavor. This tomato gratin is packed with ingredients that truly enhance the end of summers best gift.
Course Side Dish
Cuisine American
Keyword Heirloom Tomato Gratin
Prep Time 20 minutes
Cook Time 24 minutes
Total Time 44 minutes
Servings 10
Calories 155kcal
Author Cathy


  • 1 clove garlic, sliced in half
  • 3-1/2 tbsps extra virgin olive oil, divided
  • 1 large Vidalia or other sweet onion
  • 1/2 tsp grated orange zest
  • 3 tbsps fresh orange juice
  • 2 tsps honey
  • 3 tsps fresh thyme, chopped, divided
  • 4 lbs mixed heirloom tomatoes, thickly sliced
  • 1-1/2 tsps table salt, divided
  • 1-1/2 tsps finely ground black pepper, divided
  • 2 cups fresh bread crumbs
  • 1/2 cup Pecorino-Romano cheese


  • Preheat oven to 425 degrees F.
  • Prepare an oven-safe, shallow, 2 quart baking dish by rubbing the inside with garlic. Paint the dish with 1-1/2 Tablespoons extra-virgin olive oil.
  • Heat 1-1/2 Tablespoons oil in a large skillet over medium heat. Add onion and cook for about five minutes or until onions are translucent, not brown. Remove from heat, stir in orange zest, fresh orange juice, honey and 1-1/2 teaspoons thyme.
  • Add half of the onion mixture to the bottom of the baking dish and half the tomatoes. Season with half the salt and pepper and add the rest of the onion mixture, tomatoes, salt and pepper. Overlap the tomato slices to fit.
  • In a separate bowl, mix together bread crumbs, 2 Tablespoons oil, 1-1/2 teaspoons thyme and cheese. Mix until all crumbs are moistened.
  • Bake for 24 minutes or until crumbs are golden and juices are bubbling.
  • Serve hot or warm.


Calories: 155kcal | Carbohydrates: 20.2g | Protein: 4.6g | Fat: 5.1g | Saturated Fat: 1.2g | Polyunsaturated Fat: 0.3g | Monounsaturated Fat: 2g | Cholesterol: 4mg | Sodium: 696mg | Potassium: 230.4mg | Fiber: 0.8g | Sugar: 5.1g | Vitamin A: 14.3IU | Vitamin C: 27.9mg | Calcium: 6.3mg | Iron: 0.3mg