Wash and trim the ends off all zucchini. Spiralize each zucchini into spaghetti size noodles (Blade C for most spiralizers). If you don't have a spiralizer, peel the zucchini with a julienne peeler.
Heat half the olive oil in a medium-sized saucepan over medium-high heat. Add the onion and cook for 2-3 minutes, until softened. Add half of the minced garlic and cook until fragrant, about 1 minute.
Add all of the sliced mushrooms and toss lightly to coat. Cover and cook for 5 minutes, until the mushrooms soften, but still have texture.
Remove lid and pour in the marinara sauce. Cook for another 5 minutes, until the sauce begins to boil and is heated through. Add red wine and crushed red pepper, if desired. Reduce heat to simmer as you prepare the zucchini noodles.
In a separate saucepan or skillet, heat the remaining olive oil over medium-high heat. Add the remaining garlic and cook until fragrant, about 30 seconds. Add in all the zucchini and toss with tongs to coat. Season generously with salt and pepper. Cook for 1-2 minutes, until zucchini begins to soften but still has texture and bite (they overcook and turn soft fast!) Remove from heat.
Divide the zucchini noodles amongst four bowls. Top each bowl with a hearty servings of mushroom marinara. Garnish with Parmesan cheese, if desired. Serve immediately.