Preheat your oven to 400°F and line a baking sheet with parchment paper.
Wipe the portobello caps clean with a damp cloth and carefully remove the stems and gills using a spoon.
Lightly brush the outside of each mushroom cap with olive oil and place them gill-side up on the prepared baking sheet.
In a large skillet over medium heat, cook the ground turkey until browned, breaking it into small crumbles as it cooks.
Add the minced garlic, sea salt, black pepper, and dried oregano to the skillet, stirring for 1 minute until fragrant.
Stir in the fresh spinach and cook just until wilted, then remove the skillet from the heat.
Divide the turkey and spinach mixture evenly between the two mushroom caps, pressing down slightly to pack the filling.
Sprinkle the tops with grated parmesan cheese and bake for 15 to 20 minutes until the mushrooms are tender.
Garnish with fresh chopped parsley before serving.