Preheat your oven to 375°F and lightly grease a small baking dish.
Boil the jumbo pasta shells in a large pot of salted water until al dente, then drain and set aside to cool.
In a skillet over medium heat, sauté the minced garlic in olive oil until fragrant.
Add the ground turkey to the skillet, seasoning with half of the salt, pepper, and oregano, and cook until browned.
Stir the fresh baby spinach into the turkey mixture until it is completely wilted, then remove from heat.
In a medium bowl, combine the turkey and spinach mixture with the ricotta cheese and the remaining seasonings.
Spread half of the marinara sauce onto the bottom of the prepared baking dish.
Stuff each cooked shell generously with the turkey-ricotta mixture and arrange them in the dish.
Top the shells with the remaining marinara sauce, shredded mozzarella, and parmesan cheese.
Bake for 20 minutes until the sauce is bubbling and the cheese has melted beautifully.