Heat olive oil (1 tablespoon) in a large skillet over medium-high heat. Add gnocchi (16 ounces) and cook, stirring frequently, for about 7-8 minutes, or until lightly browned. Remove from pan. Add the Italian sausage (12 ounces) to the skillet, and cook until no longer pink. Add the diced tomatoes, garlic (2 cloves), dried basil (1 teaspoon), dried oregano (1/2 teaspoon), salt (1/2 teaspoon) and black pepper (1/2 teaspoon) to the pan. Bring to a simmer. Return the gnocchi to the pan. Stir in heavy cream (1/3 cup), and cook a few minutes more, until everything is heated through. Top with mozzarella cheese (1 cup). Turn down the heat to low or turn off, and cover until cheese is melted and bubbly. Sprinkle with fresh parsley (1-2 tablespoons) before serving.