"They didn't shut up," West Chester East coach Drew Cox said. "It means everything to steal it away from the West."
The win ended Quaker Valley's 46-game winning streak, which included last year's Class A final, and gave East its first title since 2008.
"It feels incredible to steal it away from them, end their streak, and bring the Cup back to the East," Cox said.
Despite firing 10 of the game's first 11 shots, East fell behind, 1-0, on Parker's goal.
The Vikings responded a minute later. Zach Higgins tied the game and the Vikings took a 3-1 lead into the first intermission when Jesse Abarca and Carter Dwyer tallied late in the period.
"They're not a team that usually stays back and plays defense," said Abarca, who had two goals and two assists. "I hope they weren't in their comfort zone. I didn't want them thinking they could win 47 in a row."
Higgins and Chris Rodier scored power-play goals in the second period to expand the lead.
Quaker Valley made a charge in the third. After Abarca scored shorthanded, Quaker Valley got three straight goals to close within one with 24 seconds left. But East held on with the help of its fans.
"If they get quiet, then players start thinking about it," Cox said. "But the crowd stayed in it and kept us fired up."
Quaker Valley 1 0 4 – 5
West Chester East 3 2 1 – 6
Goals: Q-Jimmy Perkins (Connor Quinn), 9:29; Perkins (Quinn, Clayton Bouchard), 4:25 (third); Alex Quinn (Adam Pilewicz), 7:13; Ryan Dickson (Bouchard, Connor Quinn); 8:04; Connor Quinn (Alex Quinn, Perkins), 16:36. WCE-Zach Higgins (Jesse Abarca, Chris Rodier), 10:29; Abarca (Gage Downing), 12:55; Carter Dwyer (Rodier, Higgins), 15:58; Higgins (Abarca, Rodier), 13:29 (second); Rodier (unassisted), 16:06; Abarca (Higgins), 6:49 (third).
Saves: Q-Parker Sherry 24, Jonathan Pijar 1; WCE-Tyler Percival 19.
Contact Nick Carroll at email@example.com. Follow on Twitter @NickJCarroll.