1-First, preheat your oven to 400 degrees F and coat a large rectangular baking dish with cooking spray. Slice the 4 medium zucchini in half lengthwise and trim the stem ends, then carefully scoop out the flesh with a spoon to make boats. Sprinkle the zucchini shells with 1/2 teaspoon dried Italian seasoning, salt, and pepper to taste, and arrange them in the baking dish.

2-Next, heat 2 teaspoons olive oil in a large pan over medium-high heat. Add 1 pound mild Italian sausage with casings removed and cook for 4-5 minutes, breaking it up into pieces until browned. Then, stir in 1/2 cup finely diced onion and cook until softened, about 4 minutes, followed by 1 teaspoon minced garlic for 30 seconds. Season the mixture with salt and pepper to taste, then add 2 cups marinara sauce and simmer for 5 minutes to blend the flavors.

3-Now, spoon the meat mixture evenly into the zucchini shells and top with 3/4 cup shredded mozzarella cheese. Bake for 25 minutes, or until the zucchini is tender and the cheese is melted and golden brown. Finally, sprinkle with 1 tablespoon chopped parsley and serve warm. This totals about 10 minutes prep and 40 minutes cooking, making the whole process 50 minutes.