Ben Foden (right, being congratulated by Chris Ashton), set Saints on their way
Northampton coach Jim Mallinder praised his team's "outstanding" first-half performance as they defeated Perpignan to reach the Heineken Cup final.
Ben Foden and Jon Clarke crossed within the opening 30 minutes as Saints eventually ran out 23-7 winners to book a final against Leinster on 21 May.
"I'm delighted. The first half was outstanding and we kept it going into the second half," said Mallinder.
"This is the biggest moment of my coaching career."
Mallinder, whose team are also in the running for the Premiership play-offs, paid tribute to what he described as "a really good group".
"You've got to play well and to play accurately and we did that today," he added.
The final is a massive challenge but that's what we're playing for, it doesn't get any bigger than Leinster in Cardiff
Northampton captain Dylan Hartley was delighted by the way his team maintained their mental focus.
"Discipline was crucial," he said. "When points are on offer teams are going to take them, we knew they had a good kicker and knew we couldn't give away any stupid penalties and I think we achieved that."
Perpignan travelled over from France with a well-deserved reputation for the power of their pack but Saints matched and then bested them in the scrum.
Hartley, however, was keen to play down Northampton's superiority in that facet of the game.
"I don't think we ever gained too much dominance," he insisted. "For the first 40 minutes no-one was moving in the scrums, but that hard work in the first half paid off later on and it started to go our way in the second half."
Hartley added that he was relishing the chance to tackle Leinster - who beat Toulouse 32-23 in their semi-final - in the final at Cardiff's Millennium Stadium on 21 May.
"To go to Cardiff is special - it's a big occasion," he said. "I've got a great team around me and it makes my job easier when you have got 14 guys around you all doing their job. I'm just happy to go to Cardiff and in knock-out rugby this team can win any game on its day."
Northampton are bidding to become the first team in history to win the final without losing a match, having won all six of their pool games.
"Obviously we've got to the final and we're still unbeaten, it's fantastic," said man of the match Phil Dowson.
"I don't know if it was domination out there. We got a good start. We took a pounding in the first 20 away to Perpignan last year and knew we had to learn from that.
"We spoke about playing a bit of territory, a few mistakes crept in from Perpignan and we took our chances.
"We wanted to keep playing at a high tempo and to get our big lads in the game.
"The final is a massive challenge but that's what we're playing for. The ambition of the club is to be playing in big finals and it doesn't get any bigger than Leinster in Cardiff."