The former Ipswich Town striker completed his move to Chelsea on Wednesday.
And the move will see Delap again working with his former academy coach at Manchester City, Maresca.
"He is an incredible coach and helped us all develop so much," Delap told the Chelsea website. "What we did that season was record-breaking, and what he’s gone on to achieve - and what the players in that age group have achieved - is incredible.
"He has a great understanding of the game. He was very detailed in how he approached things with us and while it can be hard at that age to take on so much information, he brought it across in a way we understood and could put into our games.
"I think it’s proved in the years since how much it has helped."
At City, Delap also played alongside Cole Palmer, now firmly established as a major player at Chelsea.
He also said: "Cole is incredible in everything he does. I can’t wait to be in front of him again and receive his passes."