Carndonagh Community School had been pegged back to 1-1 by half-time but Christy McLaughlin-Fildara settled in extra-time with a sublime strike.
Cushioning Evan Tweed’s diagonal pass towards goal on the left side, the winger unleashed a ferocious volley which thundered into the far corner.
PBS, better known in the sporting sphere for their rugby rather than football prowess, had matched the northerners for long spells only for sloppy finishing to ultimately cost them.
David Dalton spurned a couple of golden chances to force a penalty shoot-out, firstly nodding over from six yards within moments of the Cork side falling behind for a second time and also blazing off-target in the dying minutes.
Carndonagh had forged ahead midway through the first half from a penalty.
Tweed was bundled over in the box by Bryan Cotter, enabling Cathal Farren to find the top-corner.
The Leesiders eventually drew level on half-time after Douwe Van Sinderen forced the ball home.
Dave Barry, son of the ex-Cork City midfielder and All-Ireland winner, created the chance for PBS.
D Houghton; J McKinney, S Todd, D Folan, B McEleney; E Tweed, J Lafferty, K Doherty (D McLaughlin 57), C Farren; C McLaughlin-Fildara, B Browne (F McClure 98).
E O’Sullivan; F O’Brien, B Cotter, B Mulcahy, C Maguire; D Van Sinderen (S O’Brien 79), D Grant-Sullivan, E Davis (E O’Leary 109), M Cunningham, D Barry; D Dalton.
David Buckley (Donegal).
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