In a large mixing bowl, combine the softened cream cheese, shredded cheddar cheese, chopped green onions, Worcestershire sauce, garlic powder, and black pepper. Mix the ingredients thoroughly until well combined.
Scoop out small portions of the mixture and roll them into bite-sized balls, about 1 to 1.5 inches in diameter.
Roll each cheese ball in the finely chopped pistachios until fully coated.
Gently press two full blue tortilla chips into each cheese ball to create the bat wings. Take two rounded edges from the chips to create the ears.
Slice black olives into small rounds. Place two olive slices on each cheese ball to create the bat's eyes. You can use cream cheese as a glue to attach the olive slices if needed.
Tip: Place the mini cheese ball bats in the refrigerator for at least 1-2 hours to allow them to firm up before serving.
Serve with more tortilla chips or anything else you prefer to dip with.