Heat a large skillet over med-high heat. If using ground turkey instead of beef, add a drizzle of olive oil first. If using beef, add right to the pan (the fat from the beef as it cooks will be enough that you shouldn't need oil).
Cook for 2-3 minutes until lightly browned, then add onion, carrots and celery if using, and garlic. Season with salt and pepper to taste. Saute for 7-8 minutes until tender, then add 3/4 of the jar of the pasta sauce, cooking another 2 minutes. Remove from heat and set aside.
Meanwhile, preheat oven to 425 F, then add ricotta and egg to a bowl and mix well to combine. Slice zucchini lengthwise into about 1/4-inch thick strips.
To a 9x13 baking dish, add a bit of the meat sauce to the bottom. Layer in zucchini noodles, then spread ricotta overtop, followed by mozzarella cheese and more meat sauce. Repeat one more time, finishing with zucchini noodles on top and reserving a bit of mozzarella for topping.
Pour the remaining 1/4 jar of pasta sauce overtop, then bake for 40 minutes. Remove from oven, top with a bit more mozzarella cheese, then bake 5 more minutes. Serve with fresh basil overtop. Enjoy!