Preheat the oven to 375°F.
Grease a 9X13 baking dish and set aside.
Cook pasta shells in boiling salted water for 2-3 minutes less than the minimum time listed on the package, about 9-10 minutes.
They should remain very firm as they will continue cooking in the oven. Rinse with cool water.
In a mixing bowl, combine the ricotta cheese, shredded mozzarella cheese, grated Parmesan cheese, beaten egg, chopped parsley, garlic powder, onion powder, salt, and black pepper.
Mix well until all ingredients are evenly incorporated.
Stuff each cooked pasta shell with a generous amount of the cheese mixture and place them in the prepared baking dish.
Pour the marinara sauce evenly over the stuffed shells.
Pour the store-bought Alfredo sauce evenly over the stuffed shells.
In a small bowl, mix the breadcrumbs with a drizzle of olive oil until evenly coated. Sprinkle the breadcrumb mixture on top of the sauces.
Drizzle olive oil over the top of the stuffed shells.
Bake in the preheated oven for 20 minutes.
Garnish with fresh basil leaves, if desired, before serving.