01 - Place cubed potatoes in a large pot of salted water and bring to a boil. Cook until fork-tender, approximately 15 minutes. Drain thoroughly and return potatoes to the warm pot.
02 - Add butter and milk to the drained potatoes. Mash until completely smooth and creamy, ensuring no lumps remain.
03 - Heat a skillet over medium heat. Sauté shredded cabbage until tender, about 4 minutes. Add sliced scallions and continue cooking for 1 additional minute.
04 - Fold the sautéed cabbage and scallions into the mashed potatoes. Season with salt and black pepper. Allow mixture to cool completely to room temperature for easy handling.
05 - Scoop approximately 2 tablespoons of cooled colcannon mixture. Flatten in your palm, place a cheddar cube in the center, and wrap potato mixture around cheese to completely enclose. Shape into a smooth ball. Repeat until all mixture is used.
06 - Arrange three shallow bowls: one with flour, one with beaten eggs, and one with panko breadcrumbs. Coat each ball in flour, dip in egg, then roll thoroughly in panko to ensure even coverage.
07 - Heat 2 inches of vegetable oil in a deep skillet or pot to 350°F. Fry balls in batches for 2 to 3 minutes, turning occasionally, until golden brown and crispy. Remove with slotted spoon and drain on paper towels.
08 - Serve hot while cheese remains melted and gooey for optimal texture and flavor experience.