Man Utd came racing out the blocks and rattled the crossbar early on in the second-half through Scanlon. Almost immediately down the other end, Matteo Dashi and Seb Williams combined well before the former got a shot away that deflected out for a corner.
On the hour-mark, Man Utd doubled their advantage through Harry Amass. The defender was on a strong run forward before a stroke of luck saw his effort across the face of goal deflect in.
Palace came close to halving the deficit after going two goals down, with the pick of the chances fell to second-half substitute and debutant Benji Casey. Excellent footwork from Jesse Derry saw the ball worked towards Joe Gibbard.
His attempts at getting a shot on goal were smothered, though he managed to find Casey who rifled a fierce attempt on goal that was parried away by Elyh Harrison.
That proved to be the best chance of the game for Palace, as Man Utd dominated the final 15 minutes of the game, scoring three times.
A double from Ethan Wheatley and one from second-half substitute Gabriele Biancheri saw the hosts progress into the final. The young Eagles fought valiantly, with the scoreline perhaps not reflecting on their efforts throughout the game.
Reaching the semi-final of the U18 Premier League Cup for the first time in the club’s history will inspire further sides to push on and go one better, however attention will now turn towards doing the best they can in the league fixtures that remain.
Man Utd: Harrison (GK), Kamason, Jackson, Munro, Devaney, Mantato (Biancheri, 69), McAllister, Wheatley, Scanlon (Thwaites, 78), Missin (Bailey, 82).
Subs not used: Myles (GK), Armer.
Palace: Hill (GK), Carindes, Grante, Jemide, Cowin (Casey, HT), King, Gibbard, S. Williams (Whyte, 62), Dashi (Austin, 62), Agbinone, Derry.
Subs not used: Eastwood (GK), Adams-Collman.