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Baked Potato And Zucchini Gratin in a glass baking dish with golden cheese crust and fresh thyme.

Baked Potato And Zucchini Gratin Recipe

A Provençal-style Zucchini and Potato Tian baked over a bed of sweet caramelized onions and garlic, seasoned with fresh thyme and rosemary, and finished with a crispy golden cheese crust.
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Prep Time 20 minutes
Cook Time 50 minutes
Servings: 6
Calories: 210
Ingredients Method Notes

Ingredients
  

For the Vegetable Layers:
  • - 3 medium Yukon Gold potatoes thinly sliced into 1/8-inch rounds
  • - 2 medium green zucchinis thinly sliced into 1/8-inch rounds
  • - 1 medium yellow onion sliced into thin strips
  • - 3 cloves garlic minced
  • - 2 tbsp extra virgin olive oil divided
  • - 1 tsp sea salt
  • - 1/2 tsp freshly cracked black pepper
For the Herb & Cheese Topping:
  • - 1/2 cup Parmesan cheese or Romano, finely grated
  • - 1/2 cup Mozzarella cheese or Gruyère, shredded
  • - 4 sprigs fresh thyme leaves stripped
  • - 1 sprig fresh rosemary

Method
 

Prep the Base & Oven:
  1. Preheat oven to 375°F (190°C). Lightly oil a glass rectangular baking dish.
Caramelize Onions:
  1. Heat 1 tbsp extra virgin olive oil in a skillet over medium heat. Sauté sliced onions for 5–7 minutes until soft and translucent. Add minced garlic and cook 60 seconds until fragrant. Spread evenly over the bottom of the baking dish.
Assemble Vegetables:
  1. In a bowl, toss sliced potatoes and zucchinis with remaining 1 tbsp olive oil, salt, pepper, and fresh thyme leaves. Tightly alternate potato and zucchini slices vertically in neat rows over the onion bed.
Stage 1 Bake (Covered):
  1. Cover tightly with foil and bake for 30 minutes until potatoes are tender.
Stage 2 Bake (Uncovered):
  1. Remove foil. Top evenly with grated Parmesan and shredded Mozzarella. Place a fresh rosemary sprig in the center. Bake uncovered for 15–20 minutes until golden brown and bubbling.
Serve:
  1. Rest for 5 minutes before serving warm.

Notes

- To prevent soggy zucchini, ensure uniform 1/8-inch slices.
- Do not use pork or wine in this recipe.
- Reheat leftovers in an air fryer or oven at 350°F to retain top crispness.