Slice the zucchini in half lengthwise. Scoop out center with a spoon to make room for the filling. Place zucchini boats on a baking sheet.

Set a skillet over medium heat. Once hot add olive oil, mushrooms, kosher salt, pepper, Italian seasoning, and crushed red pepper flakes. Cook 4 to 5 minutes. Add spinach and garlic, cook 2 more minutes. Add more olive oil if needed.

Remove from heat and stir in half of the mozzarella and parmesan cheese.

Season the zucchini boats with kosher salt and pepper. Add the cheesy mushroom filling to the zucchini boats.

Bake the zucchini boats in a 425 degree oven for 20 to 25 minutes. Sprinkle remaining mozzarella and parmesan cheese over top during the last 3 minutes.