Blend together the cream cheese, cheddar cheese, onion, and salsa.
Scoop onto plastic wrap and use the wrap to form the mixture into a 5-inch pumpkin-shaped ball; chill at least 2 hours (I chilled mine over night). To serve, unwrap, roll in crushed nacho-flavored tortilla chips and press a bell pepper stem into the top.
To make some pumpkin lines, I used some string, held it at the "pumpkin stem and pressed it into the pumpkin.
Notes
For our pumpkin-shaped cheeseball, you can make it up to a week ahead of time and still have a great appetizer to serve!