The striker also set up two goals as the Toffees ran out 5-0 winners in their second-round match at Goodison Park.
"Kevin gave us a cameo of what he's about with his speed, his movement and his finishing," Round told the club's official website. "He showed why he was one of the top goalscorers in Greece.
"That is why we have got him at the club. He tired quite badly in the second half but we expected that. He missed quite a chunk of pre-season with a knee injury. He's not really up to speed yet but he is getting there."
Mirallas signed a four-year deal with Everton earlier this month following a two-year spell with Olympiakos.