The 20-year-old midfielder, who spent the last campaign on loan at Birmingham City, scored during the Hammers' 3-2 friendly win over Sporting Clube de Portugal on Monday.
"The lad has got ability," Nolan told the club's official website. "It was all the off-field stuff and his mental attitude to the game and I think he has come back [with a renewed approach].
"Hopefully now this will be the start of what is going to be a fantastic career for him, because as you can see he has great ability and can score goals too.
"I'm going to help him as much as I can this season, talking to him on the pitch and off the pitch. If he can get it all right, he'll be a top player for years to come."
West Ham start the new Premier League campaign at home to Cardiff City on August 17.