Preheat your oven to 400°F and line a baking sheet with parchment paper.
Clean the portobello mushrooms by removing the stems and gently scraping out the gills with a spoon.
In a large skillet over medium heat, add the olive oil and ground turkey, breaking it apart as it cooks.
Add the minced garlic, dried oregano, sea salt, and black pepper to the skillet, sautéing until the turkey is browned.
Stir in the fresh chopped spinach until it is completely wilted, then remove the skillet from the heat.
Place the mushroom caps on the baking sheet and fill each generously with the turkey and spinach mixture.
Bake for 15-20 minutes until the mushrooms are tender and the filling is hot.
Remove from the oven, drizzle with balsamic glaze, and sprinkle with parmesan cheese before serving.