Step 1: Ensure cheeses are at room temperature. In a large mixing bowl, combine the grated extra-sharp cheddar and sharp cheddar cheeses.
Step 2: In a separate small bowl, whisk together the softened cream cheese and mayonnaise until smooth and creamy. This helps prevent lumps and ensures an even distribution.
Step 3: Add the drained diced pimentos, grated onion (if using), Worcestershire sauce, smoked paprika, garlic powder, and cayenne pepper to the mayonnaise mixture. Stir until thoroughly combined.
Step 4: Pour the mayonnaise mixture over the grated cheeses. Using a sturdy spoon or a rubber spatula, mix well, ensuring all the cheese is coated. Be gentle but thorough; you want a cohesive spread, not a paste.
Step 5: Season the pimento cheese with salt and freshly ground black pepper to taste. Start with a small amount, mix, and then taste. Adjust as needed.
Step 6: Transfer the masters pimento cheese recipe mixture to an airtight container. Cover and refrigerate for at least 1 hour, or preferably longer, to allow the flavors to meld. This step is crucial for the best taste.
Step 7: Before serving, let the pimento cheese sit at room temperature for about 15-20 minutes to soften slightly, making it easier to spread. Serve with crackers, celery sticks, or on classic white bread.