Two goals in four second half minutes, courtesy of Kelland Watts' penalty and Cal Roberts' calm finish, gave United breathing space before Elias Sørensen's 20th goal of the season secured the Magpies' spot in the final, setting up a clash with either Swansea City or Everton.
Dawson's squad have already enjoyed an impressive season so far, after reaching the Checkatrade Trophy last 16 and qualifying for the Premier League 2 Division Two play-offs, and the coach was pleased to progress past the semi-final stage against a Leeds squad boasting first team and international experience.
He told nufc.co.uk: "I'm really pleased for the group of lads. They have all been fantastic this season and I think it's a just reward for the hard work and effort they've put in over the course of a long season so far.
"The timing of the goals were very important. At half-time, we mentioned that we had only done half of the job. The quality of the pitch wasn't great and didn't suit the way we wanted to play so we had to adapt to that.
"We tried to play a bit more on the break and got some great opportunities from pressing high up the pitch when they were trying to play and the ball was bobbling around. We knew that would give us chances and the pace we have up front helped.
"The goals gave us a bit of impetus at the start of the second half and something to hang onto, which forced our opponents into opening up more.
"It's a really good group who rise to the big occasions. We saw that in the Checkatrade Trophy when we played against Football League sides and senior players, seeming to get the bit between their teeth and giving it a go.
"For them going forward, it proves they can compete at first-team level wherever that is. Hopefully, we can keep developing and improving them as individuals so they can make that step sooner rather than later."
After a heavy 5-0 league defeat against Manchester United, Dawson was pleased with the strong reaction from United's second-string after a footballing lesson against the Red Devils at St. James' Park.
The under-23s coach commended the team's efforts for both the semi-final victory and throughout their lengthy campaign as the young Magpies target promotion to Premier League 2's top division and a maiden Premier League Cup title.
Dawson said: "I think they had a bit of a point to prove and I thought the result last week, against a very good Man United team, gave them a kick up the backside, reminding them where they are at. I don't think you can come away from a defeat like that at St. James' Park and not learn things.
"You can't ease off and have to keep working hard day in, day out. The response in training has been great so there was no surprise that we got that display against Leeds.
"No matter what happens, it's already been a great season. More importantly, from an individual's point of view, the progress and improvement that we've seen in the group of players that we have and those who have been lucky enough to get chances with the first team has been excellent, with Sean (Longstaff) being the stand out person from the group who has made that leap.
"It would be nice for the squad to have something to remember the season by but, overall, everyone at the Academy have been really pleased with how this group have progressed as a lot of them have been in the system for many years."
