Preheat your oven to 350 degrees Fahrenheit. Line a rimmed baking sheet with parchment paper.
Scoop out the insides of the zucchini with a spoon or melon baller, leaving about 1/4 inch around the outside of the zucchini. Chop up the zucchini that you pulled out. 3 to 4 medium zucchini
Combine half the chopped zucchini (see note), bread crumbs, sausage (raw), cheese, eggs, parsley, 2 minced garlic cloves, salt and pepper in a large bowl.
1 cup Italian seasoned bread crumbs, 1 pound spicy Italian sausage, 1/4 cup Parmesan cheese, 2 eggs, 4 cloves garlic, 2 tablespoons chopped fresh parsley, 1 teaspoon kosher salt, 1/2 teaspoon black pepper
Fill the zucchini with the mixture, place onto the prepared baking sheet, and bake for 40 minutes.
While the zucchini cooks, make a sauce. Heat oil in a sauce pan. Add 2 minced garlic cloves and sauté for about 30 seconds. Then add in the crushed tomatoes. Bring to a boil, and then reduce to a simmer. Add in the basil, oregano, salt, and pepper. Continue simmering for 15 minutes. At the end of the simmering time, taste the sauce. If it seems a little tart, add a teaspoon of sugar. This will even out the acidity of the canned tomatoes without making the sauce sweet.
4 cloves garlic, 1 tablespoon olive oil, 28 ounces crushed tomatoes, 1 tablespoon dried sweet basil, 1 tablespoon dried oregano, 1 teaspoon kosher salt, 1/4 teaspoon black pepper, 1 teaspoon sugar
After 40 minutes, top the zucchini with the sauce and mozzarella cheese. Put it all back in the oven for 10 to 15 minutes.
1 cup mozzarella