In a large bowl mix together cream cheese, white cheddar cheese, dijon mustard, and garlic powder until well combined. Mix in chopped cranberries.
Lay a large piece of plastic wrap out on a flat surface. Scoop the cheese mixture out of the bowl and place it in the middle of the plastic wrap. Wrap the plastic around the cheese mound, then use your hands to shape it into a ball. Chill for at least 1 hour.
Unwrap the cheese ball and using small handfuls of nuts at a time, press the chopped pistachios onto the outer surface of the cheeseball. (You don't need to cover the bottom of the cheeseball with nuts).
Place on a plate and serve with crackers, or cover and chill until ready to serve.
Pro tip: I like to serve this with a good, sturdy cracker like Wheat Thins or Triscuits.