Provençal Zucchini Gratin

1. Preheat Oven and Prepare Dish

Preheat your oven to 425°F and grease an 8x10-inch oval gratin dish with butter.

2. Cook Onion

In a medium pot or Dutch oven, melt 3 tablespoons of unsalted butter and cook one large yellow onion until tender and translucent, about 10 to 15 minutes.

3. Cook Zucchini

Add sliced zucchini and 2 teaspoons of kosher salt to the pot, cover and cook for 15 minutes, then uncover and cook for another 10 minutes, stirring occasionally.

4. Thicken with Flour and Half-and-Half

Sprinkle 1 tablespoon of all-purpose flour over the zucchini, stir, and gradually pour in 1 cup of half-and-half, bringing the mixture to a gentle boil.

5. Season the Mixture

Remove the pot from the heat and stir in minced fresh thyme leaves, ground nutmeg, 1 teaspoon of kosher salt, and freshly ground black pepper.

6. Transfer to Gratin Dish

Transfer the zucchini mixture into the prepared gratin dish, spreading it out evenly.

7. Add Topping and Bake

Combine bread crumbs with grated Gruyère cheese and sprinkle over the zucchini mixture. Dot with remaining 2 tablespoons of butter and bake for about 20 minutes until browned and bubbling.