The former Bournemouth man netted twice on his first start for Gareth Southgate's men as they beat San Marino 9-0 on Tuesday night.
"It means the world to me to make my full debut for the England Under 21s and to cap it all off with a couple of goals means so much," he told Burnley's official website.
"For my family and me, it's one of the biggest achievements I'll ever have.
"I knew there were going to be opportunities for me to get a goal on my debut and I am glad I took them.
"I'm delighted to get the two, but I felt I could have had more. On another day I could have had four or five but I am happy to come off the pitch with two.
"But I can't complain. I'm playing for the England Under 21s and I've scored a brace."