Wipe mushroom tops off with a wet towel and pick out the stems. In a medium skillet on medium-high heat, cook turkey meat through. Add chopped onions and seasonings. Cook until just about done, remove from heat and drain. Add 2 cups of cheese and mix together. Spoon mixture into mushrooms and place them on a baking pan or cookie sheet. Top with reserved cup of cheese. Place in 350 F oven for about 15 to 20 minutes, or until cheese is melted and mushrooms are soft.

Remove stems from mushrooms and dice. Heat oil in skillet. saute diced stems with garlic until softened. Remove skillet from heat. Stir in seasonings and cheese. Stuff into mushroom shells. Place in slow cooker. Cover. Heat on low 2 to 4 hours.