Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Clean the portobello mushrooms by wiping them with a damp cloth, then carefully remove the stems and scrape out the dark gills with a spoon.
Mince the garlic and finely chop the fresh parsley.
In a non-stick skillet over medium heat, add the olive oil and sauté the ground turkey with the minced garlic until the turkey is fully browned and cooked through.
In a small mixing bowl, combine the cooked turkey, Greek yogurt, fresh parsley, sea salt, black pepper, and dried oregano until well mixed.
Place the mushroom caps on the prepared baking sheet, gill-side up, and divide the turkey mixture evenly between the two caps.
Sprinkle the grated parmesan cheese over the top of each stuffed mushroom.
Bake for 15-20 minutes until the mushrooms are tender and the cheese topping is golden brown.
Let rest for 2 minutes before serving to allow the juices to settle.