Lightly grease the inside of a 9x12-inch baking dish with the butter. Preheat the oven to 350°F.
Prepare the spaghetti according to the package directions and under cook by 2 or 3 minutes. It should be very al dente. Drain and rinse with cool water. Set aside.
Beat the eggs lightly to combine. Stir in the grated parmesan cheese, extra virgin olive oil, finely minced garlic, parsley, salt and pepper.
Be sure not to add too much salt as the cheese has plenty of salt already.
Add the egg mixture to the spaghetti and mix until all the spaghetti is well blended with the eggs. Pour into the buttered baking dish and spread the spaghetti mixture evenly in the pan. Cover with foil and bake for 40 minutes or until the eggs are completely set. Uncover the spaghetti pie and sprinkle the shredded mozzarella cheese over the top and bake, uncovered, for another 5 minutes or until the mozzarella is melted and slightly browned. Remove from the oven and cool.