A haul of 2-4 from teenage star Deirbhile McCaffrey helped Cornafean overcome a seven-point first-half deficit to claim the ladies JFC title in a thrilling final at Kingspan Breffni.
A fantastic contest came down to a shoot-out between young stars McCaffrey and Ashling Gilsenan, with Cornafean just doing enough to get over the line.
Mountnugent-Munterconnaught began full of running and clever use of the ball and they looked the likelier winners when they raced into a 2-5 to 0-4 lead after 18 minutes but the 'Redettes' had cut the gap to four by the break and ran out three-point winners after a pulsating second half.
Early on, it was all about Mountnugent-Munterconnaught. While McCaffrey opened the scoring for Cornafean in the second minute, a goal from Ruth Gilsenan followed by two points from Ashling Gilsenan (one free) saw the Meath border side take control five minutes later.
Rebecca Smith hit back with a super point for Cornafean on nine minutes but midfielder Kate O'Reilly replied with a point via the post, following good work from Emma McCabe and Saoirse O'Reilly.
Better was to follow when the reliable Ashling Gilsenan added another right-footed free from 20 metres to edge underdogs Mountnugent/Munterconnaught, who were set up defensively and counter-attacking well, into a five-point lead.
McCaffrey got the scoreboard ticking over again in the 16th minute for Cornafean when she grabbed a pass from Rebecca Dunne and drilled her shot inches over the bar.
Kate O'Reilly then fired over with the left boot for her second point and although Ashling Smith replied with a point after great approach play by Kellie Johnston, from another turnover, they would raise their second green flag.
They won their own kick-out and went long to Ashling Gilsenan, who took on her marker and laid off for the on-rushing Emma McCabe, who flicked out to the left for Ellen O'Reilly to smash home.
Rebecca Dunne immediately hit back for Cornafean but this was quickly cancelled out when, after Ashling Gilsenan hit the woodwork, McCabe fired over another.
Youngster Gilsenan added another from play but the eventual winners finished the half well with a brilliant long-range goal from McCaffrey, who gathered the ball 40 metres out and belted home with the left from 20 metres.
McCaffrey added another point two minutes later as the sides went in at half-time with Mountnugent-Munterconnaught leading by 2-7 to 1-6.
Cornafean began the second half on the front foot, despite strong defending from Mountnugent-Munterconnaught, and within four minutes of the restart the would-be winners were back within one when, after a 45, Aisling Smith's powerful shot found the net.
A minute later, the sides were level when Roisin Barry tied it up with a well-taken point. Back came their opponents with an excellent point from play by Kate O'Reilly but Cornafean hit the front for the first time in half an hour of play when the brilliant McCaffrey took a pass from Wilson and buried a magnificent strike to the back of the net.
And the drama continued when Ashling Gilsenan got on the end of a sweeping move, galloped into space and planted a rocket to the onion bag to make it a one-point game once more.
In the 41st minute, Cornafean drew level once again when Rebecca Smith slotted over to make it 3-8 apiece.
The in-form McCaffrey landed another, winning the ball well after a cross-field Kelly Johnston pass, to edge Cornafean in front on the three-quarter mark and, amazingly after such a high-scoring opening 45 minutes, there followed 15 scoreless minutes as fatigue kicked in.
The play continued to flow from end to end but both defences were on top in the final quarter, with Amy Wharton finally breaking the deadlock in the 61st minute with a sweetly-struck free after a foul on Catherine Sheridan.
In the dying seconds, as Mountnugent-Munterconnaught searched for a goal, Declan Beard's side hit them on the break and although McCaffrey sent over a 'point', the whistle had blown for a foul and midfielder Wharton made no mistake as she sealed the win after a momentous contest.
Cornafean: Aoife Miney, Nicole Kilkenny, Edel Sheridan, Ciara Duffy, Jemma Wilson, Siobhán King, Deirdre Tully, Bronach McGovern, Amy Wharton (0-2f), Ashling Smith (1-1), Roisin Barry (0-1), Rebecca Smith (0-2), Deirbhile McCaffrey (2-4), Rebecca Dunne (0-1), Kellie Johnston
Mountnugent/Munterconnaught: Roisin Campbell, Grainne McEntee, Niamh Plunkett, Lauren Gilsenan, Emma Cullen, Chloe Smith, Ellen O'Reilly (1-0), Kate O'Reilly (0-3), Emma McCabe (0-1), Sarah Gilsenan, Ruth Gilsenan (1-0), Rachel Daly, Saoirse Reilly, Zoe Maguire, Ashling Gilsenan (1-4, 2f)
Subs: Eimear Keogan, Emma Hetherton
Ref: Kieran McCarville (Cootehill)