The 20-year-old striker was recalled from his loan spell at Oxford United earlier this month, having netted four times in 22 appearances across all competitions for the U’s.
Scarlett opened the scoring for Spurs on his first appearance for the club since his return, four minutes after coming on as a 66th minute substitute for Romanian defender Radu Dragusin.
The former United loanee then grabbed an assist for Damola Ajayi with six minutes to go, while Mikey Moore netted a third in stoppage time for Spurs, who progressed to the round of 16.
READ ALSO: New book reveals stories from great and good about U’s legend
Scarlett told TNT Sports after the game: “It’s amazing. I’ve been waiting for that moment for a long time. I’ve been on loan and got to experience men’s football, and I feel really good now. I’m ready to kick on.
“I’ve been training hard, with a clear mind, and just focusing on getting my opportunity. Today it came, and I’m grateful, and I’m happy the team won.”
Scarlett has now made 18 appearances in all competitions for Spurs, with 15 of those coming as a substitute.