Preheat oven to 400 degrees.
Mist a 9x13 baking dish with cooking spray.
Arrange mushrooms, cavity side up, in dish.
Chop mushroom stems finely.
Melt butter in a medium skillet over medium-high heat.
Add onion, chopped mushroom stems and turkey sausage crumbles.
Sprinkle with salt and cook, stirring often, about 5 minutes.
Transfer turkey sausage mixture to a bowl.
Let cool for 10 minutes, stirring occasionally.
Stir in bread crumbs and parsley.
Fold in goat cheese.
Season with salt and pepper.
Sprinkle mushroom caps with salt and pepper.
Spoon filling mixture into mushrooms, piling in center.
Bake until lightly browned on top, about 15 minutes.
Let cool slightly before serving.