Young scrambled home a 14th-minute equaliser to cancel out Sergio Aguero’s early opener and then crossed for Marouane Fellaini to head United in front.
A dominant second-half display from United followed and Van Gaal, who has made a habit of not singling out individuals throughout his Old Trafford tenure, highlighted the former Aston Villa winger's contribution.
"I think Ashley Young was man of the match," he told Sky Sports.
"He was very good. He was involved with the first three goals - very important goals.
"And he did his job as a left winger."
United ended a run of four consecutive derby defeats and Van Gaal suggested that the party atmosphere at Old Trafford hindered some of his tactical planning during the closing stages of Sunday's match.
An injury forced the influential Michael Carrick from the field, causing United to conclude the match with 10 men - a numerical disadvantage the Dutchman claimed some of his players were unaware of.
"I must bring Carrick off the pitch because he was a little bit injured," he explained.
"It was a little bit stupid from me - all of my players were working very hard and some of my players didn’t know that we were playing with 10 men.
"The crowd is yelling and it's very difficult to bring the message."
