Cotterill gave the striker his first pro deal while at Burnley.
He told the Daily Echo: "I first saw Jay when he was playing in Burnley's youth team and he was about 15.
"He was quite a tall, skinny boy and hadn't really filled out.
"I thought straightaway he had promise and brought him straight in to train with the first team and he fitted in very comfortably. He has always been a fantastic boy, very level headed, always wanted to learn.
"Jay wants to be a really good player and he is prepared to work hard to achieve that. He would always stay back after training to work on things and he has always struck a lovely ball and always been a threat in the air with really good heading ability.
"I always had a gut feeling from the first time I saw him that Jay was going to make it to the top level and do well there.
"Right now he will be finding there is a step up in level but Jay will play in the Premier League regularly and do very well."