Preheat oven to 350°F.

Slice the zucchini in half lengthwise and use a spoon to remove the pulp, leaving about ¼ inch border along the shell.

Reserve the pulp and set aside to use in the filling mixture.

Brown the sausage, breaking apart as it cooks, in a small skillet. Add the diced onion to the sausage as it cooks to soften.

Next, add the pulp from the zucchini and saute, about 4 minutes.

Add the sausage mixture to a small mixing bowl then add the bread crumbs or crushed crackers, the grated Parmesan cheese, and seasonings. Stir to combine. Taste for seasoning and adjust if needed.

Next, add the egg and mix to combine.

Use a spoon to add the filling mixture to each of the zucchini shells and place in a baking dish or on a lined sheet pan.

Bake for 35 minutes then top with shredded cheddar cheese and bake for an additional 10 to 15 minutes, or until the cheese is melted.