Preheat oven to 375 degrees F.
Cook the shells 2 minutes less than the minimum recommended time.
Meanwhile, add the ricotta, 1 1/2 cups of the mozzarella, 1 cup of parmesan, egg yolks, grated or minced garlic into a large mixing bowl and stir to combine.
Add chopped veggies and stir to combine well. Set aside.
Drain the pasta and rinse under cold water (you will have more than will fit in the pan).
Spread half the marinara evenly on the bottom of a 9×13 inch baking dish.
Stuff 1-2 tbsp. filling into each shell and place in a single layer in the baking dish. Repeat until you’ve used up all the room in the baking dish (~20-24 shells) then top with remaining marinara and cheese.
Cover with foil and bake for 30 minutes.
Remove foil and bake another 15-20 minutes, uncovered, or until cheese is melted.
Top with fresh basil then serve.