Preheat your oven to 375°F (190°C).

Drizzle two tablespoons of olive oil across the bottom of a 9x13-inch baking dish.

Layer the thinly sliced Yukon Gold potatoes in the bottom of the baking dish.

In a bowl, combine sliced tomatoes, ½ cup tomato sauce, half of the minced garlic, one teaspoon of olive oil, and one teaspoon of Italian seasoning.

Spoon the seasoned tomato mixture over the potatoes.

Layer the sliced zucchini over the tomatoes.

Toss any remaining zucchini slices with leftover garlic and herbs, then arrange over the zucchini layer.

Drizzle remaining olive oil and pour the rest of the tomato sauce over the layers, then season with salt and pepper. Sprinkle the grated Parmesan cheese on top.

Bake for about 60 minutes or until the top is golden brown and bubbly.

Let the gratin rest for about 10 minutes before serving.