Cut bacon into small pieces and cook in heavy bottom dutch oven or pan over medium high heat until crisp. Transfer cooked bacon to a paper towel lined plate to drain. Discard all oil from pan except for the last remaining tablespoon.
Clean any dirt off mushrooms with a dry brush. Slice the very bottom of the stem off and discard. Gently press the remaining part of the stalk until it snaps away from the cap. Set aside, and then chop up all of the stems while leaving the caps whole.
Cook chopped stems over medium heat in the remaining bacon fat for 3-5 minutes, then add garlic and cook for another 2 minutes.
Combine cooked stems and garlic with blue cheese, cream cheese, chives, and cooked bacon in a bowl.
Preheat oven to 375 degrees F. Fill each mushroom cap with a small spoonful of cheese mixture. Do not overfill. Cook in preheated oven for 20 minutes, or until you see the cheese start to melt. Serve warm and garnish with additional chives.