Snow delayed the start of the 2015 installment of the Beanpot. But it was made up for with an instant classic Tuesday night between BU and Harvard to open the Beanpot, a game well worth the wait.

In one of the longest games in program history, the Terriers emerged with a 4-3 double-overtime win to advance to their first Beanpot final since 2012. The game marked the fourth game to go more than 80 minutes in the 63-year history of the tournament, and the first since 2005. It was the first time such a game involved BU since 1965, when they went three overtimes with Northeastern in a 5-4 Terriers win.

The game was ended 2:18 into the second overtime, when Danny O’Regan scored his team-leading 18th goal to seal the win. Evan Rodrigues, down in the left corner, threw a pass to the Harvard crease, where the junior was on the doorstep to bury the game-winner.

There couldn’t have been a better candidate to score the game-winning goal than O’Regan. The junior, who grew up in Needham watching the Beanpot every February, will be playing for the pot of beans for the first time in scarlet and white. The goal also clinched his first collegiate win against his brother Tommy, who is a senior forward for the Crimson. He was winless in five chances entering the game.

“Really excited to get to a Beanpot final,” said O’Regan, whose father, Tom, was the 1982 Beanpot MVP playing for BU. “Obviously it’s been a dream of mine to win one. First step was today, and it happened to be against my brother, which I’ll make sure not to bring up too much at home.”

Through 82 minutes of hockey, the Crimson left the country’s most potent line virtually scoreless. A threesome that contributed an aggregate 4.3 points per game through BU’s first 24 games of the season had just one point prior to O’Regan’s deciding tally — an assist from Rodrigues, who now has 19 assists in his last 10 games.

“They had chances,” said BU head coach David Quinn about his top line, that peppered Harvard goalie with 25 shots Tuesday. “But they waited until the last minute to really make an impact on the scoresheet.

Making the impact on the scoresheet once again was the Terriers second line of Ahti Oksanen, Robbie Baillargeon and Cason Hohmann. After recording his first career hat trick in Friday night’s 9-5 win over UMass, Oksanen assisted on Hohmann’s goal to open the scoring at 16:50 of the first period before tying the game at 3-3 with 22 seconds remaining in the second period. Hohmann picked up the assist on Oksanen’s goal, as well as Baillargeon, who now has seven points (0-7–7) in his last eight games. The sophomore from Enfield, Conn., who was drafted by the Ottawa Senators in 2012, has regained his 2013-14 form, when he put up 27 points in 35 games, since returning in January from an injury that sidelined him for nearly two months.

“Early on, I thought Ahti [Oksanen], Jack [Eichel], and Danny [O’Regan] really had a connection, they were putting up points at an alarming rate for other people and we were very happy with it,” said Quinn, who bumped had Oksanen with Eichel and O’Regan to start the season before bumping him down the second line. “And then things kind of slowed down a bit and we got Robbie [Baillargeron] back. We’re always tinkering with lines and chemistry and trying to find the right combinations.”

The Terriers certainly weren’t afraid to shoot the puck Tuesday night. Coach Quinn’s club fired 123 shots, 67 of which were on net. Michalek put in a full day at the office and then some, stopping a Beanpot-record 63 shots.

BU really got down to work after Sean Malone scored at 8:28 of the second period to give the Crimson a 3-1 lead. The Terriers would go on to score three unanswered goals by Nikolas Olsson, Oksanen and O’Regan — to answer three unanswered tallies from Harvard, scored by Kyle Criscuolo, Alexander Kerfoot and Malone. BU outshot Harvard 47-15 in the process.

“I thought early in the second we really got away from playing responsible hockey,” said Quinn. “We were just giving up odd-man rush after odd-man rush and just playing pond hockey. Then we just settled down a little bit during a TV timeout and talked about [how] we don’t need to get two in a shift, just keep playing the right way, playing responsible, and trust each other.”

The Terriers end a five-game Beanpot losing streak with the win. It marked the first Beanpot win since February 2012, also against Harvard.

BU leads the four tournament participants (Harvard, BC, Northeastern) with 29 titles. The 30th seems to be the hardest to win, however, as the Terriers haven’t won it all since 2009. The six-year drought is the longest since the program went eight years between Beanpots, from 1958-66.

“We haven’t had much success in the Beanpot since I’ve been here,” said Hohmann, a senior. “I wasn’t nervous but I every time [Harvard] had a shot on net I was like ‘please don’t trickle in’. But I think we worked really hard and everyone’s really excited. We just can’t wait to go play in the finals next week.”

The Terriers face Northeastern, playing for their first Beanpot title since 1988, Monday night at 7:30. BU is making its first appearance since 2012, when they lost an overtime classic to BC, 3-2, on a Bill Arnold goal with six seconds remaining in the first extra period.