To the bowl of a stand mixer fitted with a paddle attachment. add the cream cheese and process until smooth. Add the shredded cheddar cheese and mix until combined. Mix in the scallions and garlic powder.
Spoon the mixture onto a piece of plastic wrap. Wrap the plastic around the cheese mixture and shape it into a ball. Chill for 30 minutes to 1 hour.
Meanwhile, make the everything bagel seasoning. (Store-bought seasoning can also be used.) Add all of the bagel seasoning ingredients to a small bowl. Stir to combine. Pour ⅓ cup of seasoning onto a plate. (Add more if needed.) Roll the chilled cheese ball in the mixture, coating it completely.
Serve the cheese ball immediately or cover and chill, removing from the refrigerator one hour before serving.