NOTE: Remember that you can use my LENTIL BOLOGNESE recipe linked above in the post for this to be vegetarian!
Heat a large pot over medium heat and add the olive oil. Add in the onions with a pinch of salt and pepper and cook, stirring occasionally, until softened, about 5 to 6 minutes. Add in the garlic and mushrooms. Stir and cook for another 5 or 6 minutes, until the mushrooms soften.
Add in the turkey and break it apart with a wooden spoon. Brown it, stirring and breaking it apart, until it's cooked through, about 6 to 8 minutes. Stir in the tomato paste, dried basil, oregano, pepper flakes and brown sugar. Cook for 2 more minutes.
Add in the wine, tomatoes and parmesan. Bring the mixture to a boil then reduce to a simmer and cover, cooking for 15 minutes (or even longer if you wish!). You can make this ahead of time, FYI!
Preheat the oven to 400 degrees F
Slice each zucchini in half lengthwise. Place them on a baking sheet. Scoop out the center using a spoon to create a well. You can discard this zucchini or stir it into the bolognese if you don’t want to waste it.
Melt the butter in a saucepan and stir in the remaining garlic. Brush the zucchini boats all over with the garlic butter. Sprinkle with salt and pepper all over over.
Fill the zucchini boats with bolognese. Top with the grated mozzarella. Bake for 20 to 25 minutes, until the cheese is melty and bubbly and golden. Serve with fresh basil and extra parmesan.