The veteran boss, 63, took Sheffield United to the semi-finals of both the FA and League Cups 10 seasons ago.
But he beamed: "This one is as good a performance and result as I have ever had in the cups.
"It was like going back in time - a great night for Leeds United once again.
"Every one of my players showed fantastic hunger and desire. There were no weaknesses.
"In fact, given all our injury problems and when you look at the form Everton have been in, it's got to be the best."