Wash and dice one whole eggplant into 1/2" thick cubes and set aside. Mince 2-3 cloves of garlic and set aside as well.
Fill a large pot with water and place over medium heat. This will give the water for the spaghetti time to come to a boil while you are making the sauce.
In a large shallow saucepan, heat light olive oil on medium heat. Add in the diced eggplant and cook for about 4 minutes or until the eggplant is soft.
Stir in the minced garlic and cook for 1 more minute. Add oil as needed.
Using a fork, slightly mash the cooked eggplant then add the crushed tomatoes, parsley, oregano, salt and pepper. Stir until combined bring to a boil. Once the sauce begins to boil, decrease the heat to low. Let the sauce simmer covered halfway until the spaghetti cooks, about 10 minutes.
Add spaghetti to boiling water and cook until al dente according to package instructions.
Once the spaghetti is cooked, remove from heat. Drain the spaghetti and add to the sauce. Remove sauce from heat and mix together until spaghetti is fully covered with the eggplant sauce.
Top spaghetti with sliced Greek olives and chopped green onions.
For optional garnish, add grated Parmesan cheese and fresh chopped basil.
Serve while still warm.