In a large mixing bowl, combine the softened cream cheese, mayonnaise, and sour cream. Use an electric hand mixer on medium speed to beat the ingredients together until the mixture is completely smooth and well-blended, with no lumps of cream cheese remaining.
Add the freshly grated cheddar cheese, drained pimentos, garlic powder, onion powder, cayenne pepper, and black pepper to the bowl. Use a sturdy spatula or a wooden spoon to fold all the ingredients together until the cheese and seasonings are evenly distributed throughout the creamy base.
Taste the dip and adjust the seasonings if desired, adding more cayenne pepper for extra heat or a pinch of salt if your cheese is not very salty.
For the best flavor, transfer the dip to an airtight container and refrigerate for at least 1 hour before serving. This chilling time allows the flavors to meld together.
Remove the dip from the refrigerator about 15 minutes before serving to allow it to soften slightly for easier dipping. Serve with crackers, vegetable sticks, or sliced baguette.