Bring a large pot of salted water to a boil. Cook manicotti according to package instructions.
Let cool and set aside.
Preheat oven to 350℉.
In a large bowl, combine the egg yolks, ricotta, mozzarella, and parmesan. Season with the salt and pepper. Mix well.
Squeeze out all excess water from the frozen spinach and chop again if desired. I would recommend it.
Add spinach and artichokes to mixture and stir well.
In a 9x13 pan, pour 1 cup of marinara sauce on the bottom of pan and spread evenly. Set aside.
Using a small baby spoon or measuring spoon, stuff manicotti with filling. Filling should be spilling out both sides.
Arrange stuffed manicotti in baking dish on top of marinara sauce. Pack tightly but not overlapping.
Pour remaining 2 cups of marinara sauce on top of stuffed manicotti.
Cover with foil and bake for 40-45 minutes.
Let pan cool about 10 minutes prior to serving.
Top with additional parmesan cheese if desired.