Preheat the oven to 3750F.
Clean the mushrooms with a damp cloth and remove the stems.
In a mixing bowl, combine the chopped spinach, feta cheese, breadcrumbs, minced garlic, salt, and pepper.
Place the mushrooms on a baking sheet, gill side up.
Spoon the spinach and feta mixture into each mushroom cap.
Drizzle the stuffed mushrooms with olive oil.
Bake for 20-25 minutes, or until the mushrooms are tender and the filling is golden brown.
Serve hot as an appetizer or a main course.
