The English playmaker capped off a fine performance with the final goal in the 3-1 victory, which booked Leicester's place in the FA Cup fifth-round.
"We delivered a decent performance, especially in the first half," Frank said. "But you always talk about how they will make a fast start in the second half.
"It was a bit of magic by Maddison - what a player by the way. His development has been fantastic.
"That assist, his reaction was so quick, his touch and decision making are incredible and so is his work rate. That's what makes him a top, top player."