Fill a large mixing bowl with cold water. Set aside. Working with one potato at a time, trim the edges to form a flat base on all (4) sides.
Next, vertically cut the potato into 1/3 inch thick slices. (You should end up with about 3 thick slices for each potato.)
Place one of the potato slices between 2 chopsticks or skewers and then make thin horizontal cuts down the length of the slice without cutting all the way through. Then, flip the potato slice over and make diagonal cuts down the length of the slice without cutting all the way through.
Transfer the accordion potato slice into the bowl with the cold water and repeat this process with the remaining potatoes for a total of 12 accordion potato slices.
Soak the accordion potato slices in the cold water for 30 to 60 minutes.
Pre-heat oven to 400F. Line a large baking sheet with parchment paper. Set aside.
In a small mixing bowl, add and mix together the oil and seasonings (paprika, salt, black pepper, garlic and onion powder). Set aside.
Rinse and drain the soaked potato slices and then thoroughly pat dry with clean kitchen towels or paper towels.
Transfer the accordion potato slices onto the prepared baking sheet. Use a pastry brush to coat both sides of the potato slices with the seasoned oil mixture.
Bake the accordion potatoes for 25 minutes, flip and bake for an additional 15 to 20 minutes or until the potatoes are golden brown with crisp edges.
Garnish accordion potatoes with fresh parsley and Parmesan cheese (optional) and serve immediately while still hot as is or with your favorite dish or sauce for dipping. Enjoy!