The Blyth-born striker broke the deadlock for the young Magpies inside the opening half hour in front of 1,447 spectators at Woodhorn Lane, a new ground record for the Northern Premier League Division One East side, before Jay Turner-Cooke's excellent free-kick doubled the visitors' advantage in the semi-final tie.
Despite Dan Maguire's strike reducing the deficit in swift fashion, United's second-string battled courageously in the closing stages against the Colliers to book their place in the final, where they will face Blyth Town at St. James' Park on Tuesday, 14th May.
"We haven't been to the final of this competition for a couple of years now so the team is happy to do that," Stephenson told newcastleunited.com. "We got an early goal, which is what we wanted. I had to assess the flight of the ball because of the wind but I thought I took it well and I was pleased to get on the scoresheet.
"I thought the difference in quality was the difference. We had that extra bit of quality which changed the game with the two goals we were able to score.
"We were disappointed to concede straight after scoring the second. We knew that was a dangerous time to do so and we should've controlled that part better but, afterwards, I thought we dealt with it well to see the game out."
Stephenson, who scored his first senior goal for his boyhood club during a 5-0 win against Al Hilal in the Diriyah Season Cup in December 2022, spent the second-half of the 2023/24 campaign on loan at South Shields, scoring eight goals in 18 National League North appearances.
The 21-year-old forward, who joined United's youth set-up as a 14-year-old, reflected on his brief spell with the Mariners and is now keen to help the young Magpies lift the Northumberland Senior for the first time since 2018.
"I enjoyed every minute of my loan with South Shields," Stephenson added. "I loved it! It has definitely benefited me as a player, going up against men every week, and tonight was against a senior team so I think it helped tonight.
"It's the first time in six years we could win the competition and we are expected to do that. We need to put that pressure aside and focus on playing our best.
"We really want to end our season on a positive and win a trophy in the Senior Cup."
