Preheat oven to 450°F. Trim 1/4-inch from ends of potatoes. Slice potatoes crosswise at 1/4-inch intervals, leaving bottom 1/4-inch of potato intact. (Need a foolproof method to achieve the Hasselback effect? Place a wooden spoon or pencil on either side of the potato to prevent your knife from cutting all the way through.)
Gently rinse potatoes, being careful not to break apart. Place potatoes, cut-side down, on a microwave-safe plate and microwave about 10 to 12 minutes until slightly softened, turning potatoes halfway through cooking.
Line large shallow baking pan with foil. Arrange potatoes, cut-side up, on baking sheet. Brush potatoes with 2 tablespoons of the olive oil. Sprinkle with 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper. Bake 30 minutes or until skin is crispy and potatoes are lightly browned.
Meanwhile, mix remaining olive oil, remaining salt and pepper, panko, Parmesan, cheddar, garlic powder, oregano, paprika, and onion powder in small bowl.
Remove potatoes from oven. Top potatoes with panko-cheese mixture, carefully pressing some of the mixture into cuts. Broil about 1 minute or until cheese is golden brown.