Freshly shred the sharp and extra-sharp cheddar cheeses into a medium mixing bowl.
Add the drained pimientos and ½ cup Duke's mayonnaise.
Sprinkle the garlic powder and onion powder lightly over the mixture.
Stir until everything is thoroughly combined.
If you'd like a creamier consistency, add a little more mayonnaise, one tablespoon at a time.
Taste and adjust the garlic and onion powder if needed.
Spread a generous amount of pimiento cheese onto four slices of soft white bread.
Top with the remaining bread, slice, and serve.