Preheat oven to 375 F.

Prep the zucchini. Slice the zucchini in half lengthwise. Use a metal spoon to scoop out the flesh of the zucchini, leaving a 1/4 inch shell. Set aside about a cup of the scooped out zucchini flesh. Reserve extra zucchini for another use.

Cook the sausage: Heat a teaspoon of olive oil in a heavy skillet to medium-high. Add sausage and cook until sausage is browned and cooked through, about 8-10 minutes. Remove sausage from the pan with a slotted spoon and set aside on a paper-towel lined plate to drain. Discard remaining grease from the pan.

In the same pan, add remaining olive oil. Add onion and zucchini and cook for 5-7 minutes, until the onion becomes fragrant and begins to brown on the edges. Add garlic and tomatoes; for 2 more minutes. Remove from heat and let cool for a few minutes.

Once vegetable mixture has cooled, add to a large mixing bowl along with sausage, oregano, parsley and cheese. Use a large metal spoon to scoop the filling into each zucchini half until all ingredients are used up. Place stuffed zucchini, skin side down, in a nonstick baking dish. Place dish in oven and carefully add about 1/4 inch water to the bottom of the pan. Cook for 45 minutes or until the zucchini is fork tender. Let cool for a few minutes before serving.