Preheat oven to 400 degrees. Wash or bush off the whole mushrooms and take the stems off. Set the stems aside except for 3 stems that you will chop up. Cook the Bird's Eye blend for 3 minutes or just until a little warm, but not cooked all the way through. Transfer the Bird's Eye blend to a medium sized bowl and mix with the cream cheese and chopped mushroom stems. Place Mushrooms bottom up and the rest of stems on a rimmed baking sheet that has been sprinkled with a little course salt (this gives the mushrooms a little seasoning. Add mixture to the inside of the mushrooms and place 1/4 of a cheese slice on top of each mushroom. Bake at 400 for 15 to 20 minutes or until mushrooms are starting to sweat and are deep grayish brown and cheese is melted.