Two-goal Chicharito wasn't the only player to shine as Adnan Januzaj and Wilfried Zaha both excelled, while at the back Rio Ferdinand and Nemanja Vidic returned to the defence to oversee a clean sheet.
United had much the better of the play throughout, with Januzaj and Zaha both prominent in attack. The former played the no.10 role with presence and panache and the latter threatened frequently on the right in his second appearance for the Reds - his first start since August.
Zaha set the tone after 13 minutes with a teasing cross for Hernandez, whose shot on the spin was deflected wide. Chicharito twice went close with first-half headers but his, and United's, opening goal came from the spot. Januzaj jinked one way and another in the box and Leroy Fer clumsily clipped his heels. Chicharito confidently sent Canaries keeper Mark Bunn the wrong way, and realistically victory never looked in doubt.
Chicharito added to his tally after the break as he headed home at the second attempt from Alex Büttner's inviting cross on 53 minutes, while Anders Lindegaard made a good save from Robert Snodgrass' header, one of the few occasions he was called into action.
Phil Jones added gloss to his own impressive midfield display by volleying in United's third on 87 minutes and in the fourth of 11 added minutes substitute Fabio bundled home the ball in a one-on-one with Bunn. Three wins in a row: David Moyes will be delighted with his biggest win as Reds boss, the gathering momentum and a cup quarter-final place secured.