Preheat your oven to 375°F (190°C) to ensure it's ready when you're finished preparing the dish.
Wash the summer squash thoroughly under running water. Then, trim off the ends and slice the squash into rounds, about 1/4 inch thick. You can also cut them into half moons if you prefer.
In a mixing bowl, toss the sliced squash with olive oil, minced garlic, dried Italian herbs (such as oregano, basil, and thyme), salt, and black pepper. Make sure the squash is evenly coated with the seasoning mixture.
Take a baking dish and lightly grease it with olive oil or cooking spray. Arrange the seasoned squash slices in a single layer in the baking dish. Try not to overcrowd them to ensure even baking.
Pour your favorite tomato sauce over the arranged squash slices. You can use store-bought marinara sauce or homemade tomato sauce. Spread it evenly over the squash, ensuring each slice gets coated.
Generously sprinkle shredded mozzarella cheese over the top of the squash and tomato sauce layer. You can also use a combination of mozzarella and Parmesan cheese for extra flavor.
Place the baking dish in the preheated oven and bake for about 25-30 minutes, or until the cheese is melted and bubbly, and the squash is tender. Keep an eye on it to prevent over-browning.
Once baked, remove the dish from the oven and let it cool for a few minutes. Garnish with fresh chopped basil or parsley if desired, then serve the Cheesy Baked Italian Summer Squash hot as a delicious side dish or even a light main course. Enjoy!