Boil the diced potatoes in water with one teaspoon salt for 15 to 18 minutes until tender. Drain thoroughly.
Mash with butter, warm milk, cornstarch, ½ teaspoon salt, and ¼ teaspoon pepper. Cool and refrigerate.
Heat olive oil in a skillet. Cook the onion until softened, then add the ground beef and brown thoroughly.
Stir in garlic, smoked paprika, Worcestershire sauce, remaining salt, and remaining pepper. Cook for one minute, then drain excess grease.
Allow the beef mixture to cool and stir in the shredded cheddar cheese.
Flatten approximately two tablespoons of mashed potatoes in your palm. Add one tablespoon of beef filling, seal completely, and shape into a cube.
Coat each cube in flour, beaten egg, and seasoned panko breadcrumbs.
Refrigerate the coated cubes for 30 minutes.
Heat frying oil to 350°F. Fry the cubes in small batches for three to five minutes until golden brown and crisp.
Drain on a wire rack, cool briefly, and serve warm with dipping sauce.