Bournemouth trailed Liverpool 3-1 with just 14 minutes of normal time to play, when they staged an incredible comeback to win the match 4-3.
Cook, who scored Bournemouth's equaliser with a wonderfully taken volley, claimed that the heroic comeback and victory over a club the stature of Liverpool made it the club's finest ever moment.
Asked but 'Sky Sports' if it was the best day in the club's history, Cook said: "By a country mile. Especially against a side like Liverpool. We've never beaten them, never come close to beating them.
"A side with that much history. It's definitely the best result I've been involved in, in football".
The defender admitted that he was "delighted" to score, but says that Nathan Ake's winning goal in injury time meant more to him than his own goal.
"I was just delighted to score, but when I had scored and was running back I was just hoping we were going to nick the draw," he said
"Never in my wildest dreams did I think we'd win it. So I'd say the fourth goal meant a lot more to me than my goal.
"It was crazy and I think the celebrations showed that".
Cook also said that the Cherries "could smell blood" as Liverpool thought they already had the match won.
"Sometimes you can smell blood and I think mentally they had gone a little bit. At 3-1 up they probably thought they'd won the game, which is very unlike a Jurgen Klopp side," he added.
"We need to kick on, have a good week's training. We have a very tricky game next week at Burnley. Hopefully we can build on this and keep climbing".