Preheat the Oven: Set the oven to 400°F (200°C) and lightly grease a baking dish with 1 tablespoon of olive oil.
Prepare the Zucchini: Slice the zucchinis into ¼-inch rounds and season with kosher salt. Let them sit for 10 minutes, then pat dry to remove excess moisture.
Sauté the Garlic: In a skillet over medium heat, warm 2 tablespoons of olive oil. Add the garlic and red pepper flakes, sautéing until fragrant, about 1 minute. Remove from heat.
Assemble the Bake: Toss the zucchini slices with the garlic mixture and spread evenly in the baking dish. Drizzle with the remaining olive oil.
Add Cheese: Sprinkle mozzarella and Parmesan cheese evenly over the zucchini.
Bake to Perfection: Bake for 15-18 minutes, or until the cheese is golden and bubbly. For extra crispiness, broil for an additional 2 minutes.
Garnish & Serve: Remove from the oven, sprinkle with fresh basil and extra red pepper flakes. Serve hot.