Preheat your oven to 375°F (190°C).
Cook the jumbo pasta shells in boiling salted water according to package directions until al dente, then drain and set aside.
In a medium skillet, heat the olive oil over medium heat. Add the ground turkey and cook until browned, breaking it into small crumbles.
Add the fresh baby spinach to the skillet and sauté just until wilted, then remove from heat and let cool slightly.
In a mixing bowl, combine the ricotta cheese, egg, 1 tablespoon of parmesan, sea salt, black pepper, and garlic powder.
Fold the cooked turkey and spinach mixture into the ricotta mixture until well combined.
Spread half of the marinara sauce on the bottom of a small baking dish.
Stuff each cooked shell generously with the ricotta and turkey mixture and place them in the baking dish.
Top the shells with the remaining marinara sauce and the remaining tablespoon of parmesan cheese.
Cover with foil and bake for 20 minutes, then remove the foil and bake for an additional 5-10 minutes until the sauce is bubbling and the cheese is lightly golden.