Preheat the oven to 375°F. Grease a 9- x 13-inch baking dish with cooking spray.

Heat a large sauté pan over medium heat.

Add 2 tablespoons oil, onions, and red pepper flakes and cook, stirring occasionally, until onions are tender, about 8 minutes.

Add remaining half tablespoon oil and mushrooms and cook, until brown, about 4 minutes.

Add tomatoes and bring mixture to a boil. Reduce heat to medium and simmer, uncovered until it thickened, about 20 minutes.

Stir in basil and salt. Let cool.

Put a third of zucchini noodles on the bottom of the prepared dish, overlapping slightly. Top with half sauce and half ricotta. Repeat layers.

Top with last third zucchini. Sprinkle black pepper, parmesan, and mozzarella.

Bake at 375°F for 50 to 60 minutes or until golden brown.