1. Preheat Oven: Start by preheating your oven to 375°F (190°C).

2. Drain Zucchini: Grate the zucchinis and place them in a colander. Sprinkle with salt and let sit for about 10 minutes to draw out excess moisture.

3. Remove Moisture: After 10 minutes, use a clean kitchen towel to squeeze out any remaining moisture from the zucchini.

4. Cook Zucchini & Garlic: Heat the olive oil in a skillet over medium heat. Add the minced garlic and sauté until fragrant, about 1 minute. Then, add the grated zucchini and cook for an additional 2-3 minutes, stirring occasionally. Remove from heat and let cool slightly.

5. Mix Custard: In a large mixing bowl, whisk together the eggs, heavy cream, cheddar cheese, Parmesan cheese, oregano, black pepper, and red pepper flakes (if using).

6. Combine: Add the cooled zucchini mixture, basil, and chives to the egg-mixture. Stir until everything is well combined.

7. Bake: Pour the mixture into a greased 9-inch pie dish or a similar sized oven-safe dish. Bake for 35-40 minutes, or until the top is golden and the quiche is set in the center.

8. Cool & Serve: Remove the quiche from the oven and allow it to cool for a few minutes before slicing and serving.