Preheat your oven to 375°F and lightly grease a small baking dish with the olive oil.
Cook the jumbo pasta shells in a large pot of boiling salted water until al dente, then drain and set aside.
In a medium skillet over medium heat, brown the ground turkey until fully cooked, breaking it into small crumbles.
In a mixing bowl, combine the cooked turkey, ricotta cheese, egg, chopped baby spinach, sea salt, black pepper, garlic powder, and dried oregano.
Spread half of the marinara sauce onto the bottom of the prepared baking dish.
Fill each cooked shell generously with the turkey and ricotta mixture and place them in the dish.
Top with the remaining marinara sauce and a sprinkle of parmesan cheese.
Bake for 20 minutes until the sauce is bubbling and the shells are heated through.