Despite being held 10-10 at half time, the North struck with three second tries to leave team manager Nigel Way delighted with his side's progress this season.
"It was a tough game against a really committed side," said Way. "They matched us point for point in the first half, but I thought we were excellent after the interval and it's great for the boys that we are in the final once again."
Owen Rees crossed for the Blues' first try with Lewis Williams converting and adding a penalty for good measure.
Owen Jones replied with a try for the North and Alex Schwarz converted and kicked a penalty to leave the sides locked together at half time.
However, it was a different story altogether after the break with the Blues scoring 25 unanswered points. Williams edged his side ahead with a penalty before Ryan Edwards, Darren Harris and Jordan Sieniawski raced in for tries.
Williams converted all two and kicked a penalty to round off an excellent all-round performance.