Add the cheddar and Pepper jack and mix gently until combined. Use a rubber spatula to scrape the bowl and make sure all the ingredients are mixed together. Stir in the pimentos Taste and mix in more of whatever you think it needs. Add more cheese if you like the pimento cheese to be less creamy; add less if you like it to be more creamy.
Refrigerate pimento cheese for at least 2 hours before serving.
Serve with crackers, small hollowed-out peppers, carrot and celery sticks, and olives. (Or make small sandwiches or even a grilled cheese with it!)
***Note: For best results, make sure the cheddar and jack cheeses are nice and cold when you mix them in.
Adapted from Pioneer Woman 's recipe