Stir together in a medium bowl cream cheese, cheddar cheese, pimiento peppers, Worcestershire sauce, ½ teaspoon salt, onion powder, garlic powder, and cayenne pepper (if using) in a medium bowl until well combined. Cover and refrigerate until firm, about 30 minutes.

Meanwhile, wearing gloves, scratch the skin of the peppers using the edge of a serrated knife or a fork. Cut the peppers in half lengthwise and scoop out the seeds and ribs with a spoon. Dry well with paper towels.

Fill each pepper half with pimiento cheese, about 1 tablespoon per pepper half. Press the cheese mixture evenly into the opening, allowing a bit of the mixture to stick above the pepper. Place stuffed peppers on a baking sheet lined with a wire rack and refrigerate for 10 minutes.

Meanwhile, place the flour, milk, and breadcrumbs in 3 separate shallow bowls. Working in batches, dunk 3 to 4 pepper halves into the milk, gently tossing to coat well. Transfer into the flour and use a fork to roll the peppers, coating well. Dust off any excess flour and place back on the wire rack. Repeat with remaining pepper halves. Refrigerate the peppers for at least 10 minutes or up to 24 hours (covered loosely with plastic wrap). When ready to cook, dunk each pepper half in the milk, coating well, then add in to the breadcrumbs, rolling and pressing to coat. Transfer to the wire rack and repeat with remaining pepper halves.

To deep-fry, heat 3 inches of oil in a large heavy-bottom pot over medium-high heat until the oil reaches 375F. Working in batches, cook 4 to 6 pepper halves until golden brown, about 3 minutes. Carefully remove from oil with a slotted spoon and dry on a clean wire rack set over a baking sheet. Repeat with remaining pepper halves. Sprinkle evenly with remaining ½ teaspoon table salt. Serve immediately.