Mix together potatoes, flour, baking powder, 3 eggs, salt, and pepper in a bowl. In another bowl, mix ground beef, onion, garlic salt, 1 egg, and bread crumbs until well-combined.
Heat oil in a skillet over medium-low heat; drop a rounded tablespoon of potato mixture into the hot skillet. Spread and flatten pancake out a little, and place about 2 teaspoons of beef mixture on top, spreading filling out almost to the edges of pancake. Drop another rounded tablespoon of potato mixture on top, and spread it out to completely cover beef. Fry until the bottom of pancake is golden brown, about 5 minutes; flip and fry other side until golden, 1 to 2 more minutes. Transfer pancake to a paper towel-lined plate. Repeat with remaining potato mixture and beef filling.