Prep. Take the cream cheese out and let it soften at room temp. Fire roast the red peppers and chop them into 1/4-inch (6mm) bits. Grate the cheddar on the big holes of a box grater.
Mix. In a big bowl, with a fork, mix together the mayonnaise, pepper flakes, salt, black pepper, and sugar. Add the cream cheese and squish it around until it is pretty well incorporated. Add the cheddar and mix until coated. Add the bell pwpper chunks and stir. Taste and add more of anything you want. I like to liven it up with a little dried chipotle. There is plenty of room for personalization. Do you prefer Miracle Whip?
Optional. Throw the whole thing into the food processor and whup it up until it is fairly smooth as shown in the stuffed tomato above. There will be some fine granular texture. That's OK.
Rest. Although pimento cheese is quick and easy to throw together, it needs a few hours, overnight is best, for the pimento flavor to migrate into everything so every bite has optimal flavor. But don't let it sit around for days. It tends to get watery.
Serve. Serve with crackers, as a sandwich, as a burger topping (highly recommended), and so much more.